Compound having fluorodibenzofuran ring, liquid crystal composition and liquid crystal display device

ABSTRACT

Provided are a liquid crystal compound satisfying at least one of physical properties such as high stability to heat or light, a high clearing point (or high maximum temperature), low minimum temperature of a liquid crystal phase, small viscosity, large optical anisotropy, large negative dielectric anisotropy, a suitable elastic constant and good compatibility with other liquid crystal compounds, a liquid crystal composition containing the compound and a liquid crystal display device including the composition. 
     A compound is represented by formula (1): 
     
       
         
         
             
             
         
       
         
         
           
             In formula (1), 
             R 1  and R 2  are independently hydrogen or alkyl having 1 to 15 carbons; and A 1 , A 2  and A 3  are independently 1,4-cyclohexylene or 1,4-phenylene; 
             Z 1 , Z 2  and Z 3  are independently a single bond; 
             Y 1 , Y 2 , Y 3  and Y 4  are independently hydrogen, fluorine or the like; and 
             a, b and c are independently 0 or 1, and a sum of a, b and c is 0 to 3.

TECHNICAL FIELD

The invention relates to a liquid crystal compound, a liquid crystalcomposition and a liquid crystal display device. More specifically, theinvention relates to a liquid crystal compound having afluorodibenzofuran ring and negative dielectric anisotropy, a liquidcrystal composition containing the liquid crystal compound, and a liquidcrystal display device including the composition.

BACKGROUND ART

In a liquid crystal display device, a classification based on anoperating mode for liquid crystal molecules includes a phase change (PC)mode, a twisted nematic (TN) mode, a super twisted nematic (STN) mode,an electrically controlled birefringence (ECB) mode, an opticallycompensated bend (OCB) mode, an in-plane switching (IPS) mode, avertical alignment (VA) mode, a fringe field switching (FFS) mode and afield-induced photo-reactive alignment (FPA) mode. A classificationbased on a driving mode in the device includes a passive matrix (PM) andan active matrix (AM). The PM is classified into static, multiplex andso forth, and the AM is classified into a thin film transistor (TFT), ametal insulator metal (MIM) and so forth.

The device is sealed with a liquid crystal composition. Physicalproperties of the composition relate to characteristics in the device.Specific examples of the physical properties in the composition includestability to heat or light, a temperature range of a nematic phase,viscosity, optical anisotropy, dielectric anisotropy, specificresistance and an elastic constant. The composition is prepared bymixing many liquid crystal compounds. Physical properties required for acompound include high stability to environment such as water, air, heatand light, a wide temperature range of a liquid crystal phase, smallviscosity, large optical anisotropy, large dielectric anisotropy, asuitable elastic constant and good compatibility with other liquidcrystal compounds. A compound having high maximum temperature of thenematic phase is preferred. A compound having low minimum temperature inthe liquid crystal phase such as the nematic phase and a smectic phaseis preferred. A compound having small viscosity can shorten a responsetime in the device. A compound having large optical anisotropy candecrease cell thickness in the device, and therefore can shorten theresponse time. A compound having large positive or negative dielectricanisotropy is preferred for driving the device at low voltage. Acompound having good compatibility with other liquid crystal compoundsis preferred for preparing the composition. The device may beoccasionally used at a temperature below freezing point, and therefore acompound having good compatibility at low temperature is preferred.

Many liquid crystal compounds have been so far prepared. Development ofa new liquid crystal compound has been still continued. The reason isthat good physical properties that are not found in conventionalcompounds are expected from a new compound. The reason is that the newcompound may be occasionally provided with a suitable balance regardingat least two physical properties in the composition. Compounds asdescribed below are reported. However, in compounds (A) and (B), amelting point is high, and the compatibility with other liquid crystalcompounds is not sufficiently high. Moreover, compounds (C), (D) and (E)do not exhibit sufficiently large negative dielectric anisotropy.

JP H10-236992 A discloses compound (A) on page 36.

WO 2015/129412 A discloses compounds (B-1) and (B-2) on page 71 and page73, respectively.

WO 2002/055463 A discloses compound (C-1) on page 27.

JP 2015-174864 A discloses compound (D) on page 26.

EP 1223210 A discloses compound (E) on page 16.

CITATION LIST Patent Literature

Patent literature No. 1: JP H10-236992 A.

Patent literature No. 2: WO 2015/129412 A.

Patent literature No. 3: WO 2002/055463 A.

Patent literature No. 4: JP 2015-174864 A.

Patent literature No. 5: EP 1223210 A.

SUMMARY OF INVENTION Technical Problem

A first object is to provide a liquid crystal compound satisfying atleast one of physical properties such as high stability to heat orlight, a high clearing point (or high maximum temperature of a nematicphase), low minimum temperature of a liquid crystal phase, smallviscosity, large optical anisotropy, large negative dielectricanisotropy, a suitable elastic constant and good compatibility withother liquid crystal compounds. In particular, the object is to providea compound having larger optical anisotropy and larger negativedielectric anisotropy in comparison with a similar compound. A secondobject is to provide a liquid crystal composition that contains thecompound and satisfies at least one of physical properties such as highstability to heat or light, high maximum temperature of a nematic phase,low minimum temperature of the nematic phase, small viscosity, largeoptical anisotropy, large negative dielectric anisotropy, large specificresistance and a suitable elastic constant. The object is to provide aliquid crystal composition having a suitable balance regarding at leasttwo of the physical properties. A third object is to provide a liquidcrystal display device including the composition, and having a widetemperature range in which the device can be used, a short responsetime, a large voltage holding ratio, low threshold voltage, a largecontrast ratio, a small flicker rate and a long service life.

Solution to Problem

The invention concerns a compound represented by formula (1), a liquidcrystal composition containing the compound, and a liquid crystaldisplay device including the composition:

wherein, in formula (1),

R¹ and R² are independently hydrogen or alkyl having 1 to 15 carbons,and in the alkyl, at least one piece of —CH₂— may be replaced by —O—,—S—, —CO— or —SiH₂, and at least one piece of —CH₂CH₂— may be replacedby —CH═CH— or —C≡C—, and in the groups, at least one hydrogen may bereplaced by fluorine or chlorine;

A¹, A² and A³ are independently 1,2-cyclopropylene, 1,3-cyclobutylene,1,3-cyclopentylene, 1,4-cyclohexylene, 1,4-cycloheptylene,1,4-phenylene, decahydronaphthalene-2,6-diyl,1,2,3,4-tetrahydronaphthalene-2,6-diyl, naphthalene-2,6-diyl,9,10-dihydrophenanthrene-2,7-diyl, 9H-xanthene-2,6-diyl or9H-fluorene-2,7-diyl, and in the groups, at least one piece of —CH₂— maybe replaced by —O—, —S—, —CO— or —SiH₂—, and at least one piece of—CH₂CH₂— may be replaced by —CH═CH— or —CH═N—, and in the divalentgroups, at least one hydrogen may be replaced by fluorine, chlorine,—C≡N, —CF₃, —CHF₂, —CH₂F, —OCF₃, —OCHF₂ or —OCH₂F;

Z¹, Z² and Z³ are independently a single bond or alkylene having 1 to 6carbons, and in the alkylene, at least one piece of —CH₂— may bereplaced by —O—, —S—, —CO— or —SiH₂—, and one or two pieces of —CH₂CH₂—may be replaced by —CH═CH— or —C≡C—, and in the divalent groups, atleast one hydrogen may be replaced by fluorine or chlorine;

Y¹, Y², Y³ and Y⁴ are independently hydrogen, fluorine, chlorine, —CF³or —CHF², and at least two of Y¹, Y², Y³ and Y⁴ is fluorine, chlorine,—CF₃ or —CHF₂; and a, b and c are independently 0 or 1, and a sum of a,b and c is 0 to 3.

Advantageous Effects of Invention

A first advantage is to provide a liquid crystal compound satisfying atleast one of physical properties such as high stability to heat orlight, a high clearing point (or high maximum temperature of a nematicphase), low minimum temperature of a liquid crystal phase, smallviscosity, large optical anisotropy, large negative dielectricanisotropy, a suitable elastic constant and good compatibility withother liquid crystal compounds. In particular, the advantage is toprovide a compound having larger optical anisotropy, larger negativedielectric anisotropy and better compatibility with other liquid crystalcompounds in comparison with a similar compound (Comparative Examples 1and 2). A second advantage is to provide a liquid crystal compositionthat contains the compound and satisfies at least one of physicalproperties such as high stability to heat or light, high maximumtemperature of a nematic phase, low minimum temperature of the nematicphase, small viscosity, large optical anisotropy, large negativedielectric anisotropy, large specific resistance and a suitable elasticconstant. The advantage is to provide a liquid crystal compositionhaving a suitable balance regarding at least two of the physicalproperties. A third advantage is to provide a liquid crystal displaydevice including the composition, and having a wide temperature range inwhich the device can be used, a short response time, a large voltageholding ratio, low threshold voltage, a large contrast ratio, a smallflicker rate and a long service life.

DESCRIPTION OF EMBODIMENTS

Usage of terms herein is as described below. Terms “liquid crystalcompound,” “liquid crystal composition” and “liquid crystal displaydevice” may be occasionally abbreviated as “compound,” “composition” and“device,” respectively. “Liquid crystal compound” is a generic term fora compound having a liquid crystal phase such as a nematic phase and asmectic phase, and a compound having no liquid crystal phase but to beadded for the purpose of adjusting physical properties of a compositionsuch as maximum temperature, minimum temperature, viscosity anddielectric anisotropy. The compound has a six-membered ring such as1,4-cyclohexylene and 1,4-phenylene, and has rod-like molecularstructure. “Liquid crystal display device” is a generic term for aliquid crystal display panel and a liquid crystal display module.“Polymerizable compound” is a compound to be added for the purpose offorming a polymer in the composition.

The liquid crystal composition is prepared by mixing a plurality ofliquid crystal compounds. An additive is added to the composition forthe purpose of further adjusting the physical properties. The additivesuch as the polymerizable compound, a polymerization initiator, apolymerization inhibitor, an optically active compound, an antioxidant,an ultraviolet light absorber, a light stabilizer, a heat stabilizer, adye and an antifoaming agent is added thereto when necessary. The liquidcrystal compound and the additive are mixed in such a procedure. Aproportion (content) of the liquid crystal compound is expressed interms of weight percent (% by weight) based on the weight of the liquidcrystal composition containing no additive, even after the additive hasbeen added. A proportion (amount of addition) of the additive isexpressed in terms of weight percent (% by weight) based on the weightof the liquid crystal composition containing no additive. Weight partsper million (ppm) may be occasionally used. A proportion of thepolymerization initiator and the polymerization inhibitor isexceptionally expressed based on the weight of the polymerizablecompound.

“Clearing point” is a transition temperature between the liquid crystalphase and an isotropic phase in the liquid crystal compound. “Minimumtemperature of the liquid crystal phase” is a transition temperaturebetween a solid and the liquid crystal phase (the smectic phase, thenematic phase or the like) in the liquid crystal compound. “Maximumtemperature of the nematic phase” is a transition temperature betweenthe nematic phase and the isotropic phase in a mixture of the liquidcrystal compound and a base liquid crystal or in the liquid crystalcomposition, and may be occasionally abbreviated as “maximumtemperature.” “Minimum temperature of the nematic phase” may beoccasionally abbreviated as “minimum temperature.” An expression“increase the dielectric anisotropy” means that a value of dielectricanisotropy positively increases in a composition having positivedielectric anisotropy, and the value of dielectric anisotropy negativelyincreases in a composition having negative dielectric anisotropy. Anexpression “having a large voltage holding ratio” means that the devicehas a large voltage holding ratio at room temperature and also at atemperature close to the maximum temperature in an initial stage, andthe device has the large voltage holding ratio at room temperature andalso at a temperature close to the maximum temperature even after thedevice has been used for a long period of time. In the composition orthe device, the characteristics may be occasionally examined before andafter an aging test (including an acceleration deterioration test).

A compound represented by formula (1) may be occasionally abbreviated ascompound (1). At least one compound selected from the group of compoundsrepresented by formula (1) may be occasionally abbreviated as compound(1). “Compound (1)” means one compound, a mixture of two compounds or amixture of three or more compounds represented by formula (1). A samerule applies also to any other compound represented by any otherformula. In formulas (1) to (15), a symbol of A¹, B¹, C¹ or the likesurrounded by a hexagonal shape correspond to a ring such as ring A¹,ring B¹ and ring C¹, respectively. The hexagonal shape represents asix-membered ring such as cyclohexane or benzene. The hexagonal shapemay occasionally represents a fused ring such as naphthalene or abridged ring such as adamantane.

A symbol of terminal group R¹¹ is used in a plurality of compounds inchemical formulas of component compounds. In the compounds, two groupsrepresented by two pieces of arbitrary R¹¹ may be identical ordifferent. For example, in one case, R¹¹ of compound (2) is ethyl andR¹¹ of compound (3) is ethyl. In another case, R¹¹ of compound (2) isethyl and R¹¹ of compound (3) is propyl. A same rule applies also to asymbol of R¹², R¹³, Z¹¹ or the like. In compound (15), when i is 2, twoof ring E¹ exists. In the compound, two groups represented by two ofring E¹ may be identical or different. A same rule applies also to twoof arbitrary ring E¹ when i is larger than 2. A same rule applies alsoto other symbols.

An expression “at least one piece of ‘A’” means that the number of ‘A’is arbitrary. An expression “at least one piece of ‘A’ may be replacedby ‘B’” means that, when the number of ‘A’ is 1, a position of ‘A’ isarbitrary, and also when the number of ‘A’ is 2 or more, positionsthereof can be selected without restriction. A same rule applies also toan expression “at least one piece of ‘A’ is replaced by ‘B’.” Anexpression “at least one piece of ‘A’ may be replaced by ‘B’, ‘C’ or‘D’” includes a case where arbitrary ‘A’ is replaced by ‘B’, a casewhere arbitrary ‘A’ is replaced by ‘C’, and a case where arbitrary ‘A’is replaced by ‘D’, and also a case where a plurality of pieces of ‘A’are replaced by at least two pieces of ‘B’, ‘C’ and/or ‘D’. For example,“alkyl in which at least one piece of —CH₂— may be replaced by —O— or—CH═CH—” includes alkyl, alkoxy, alkoxyalkyl, alkenyl, alkoxyalkenyl andalkenyloxyalkyl. In addition, a case where two pieces of consecutive—CH₂— are replaced by —O— to form —O—O— is not preferred. In alkyl orthe like, a case where —CH₂— of a methyl part (—CH₂—H) is replaced by—O— to form —O—H is not preferred, either.

An expression “R¹¹ and R¹² are independently alkyl having 1 to 10carbons or alkenyl having 2 to 10 carbons, and in the alkyl and thealkenyl, at least one piece of —CH₂— may be replaced by —O—, and in thegroups, at least one hydrogen may be replaced by fluorine” may beoccasionally used. In the expression, “in the groups” may be interpretedaccording to wording. In the expression, “the groups” means alkyl,alkenyl, alkoxy, alkenyloxy or the like. More specifically, “the groups”represents all of the groups described before the term “in the groups.”The common interpretation is applied also to terms of “in the monovalentgroups” or “in the divalent groups.” For example, “the monovalentgroups” represents all of the groups described before the term “in themonovalent groups.”

Halogen means fluorine, chlorine, bromine and iodine. Preferred halogenis fluorine and chlorine. Further preferred halogen is fluorine. Alkylof the liquid crystal compound is straight-chain alkyl or branched-chainalkyl, but includes no cyclic alkyl. In general, straight-chain alkyl ispreferred to branched-chain alkyl. A same rule applies also to aterminal group such as alkoxy and alkenyl. With regard to aconfiguration of 1,4-cyclohexylene, trans is preferred to cis forincreasing the maximum temperature. Then, 2-fluoro-1,4-phenylene meanstwo divalent groups described below. In a chemical formula, fluorine maybe leftward (L) or rightward (R). A same rule applies also to anasymmetrical divalent group formed by removing two hydrogens from aring, such as tetrahydropyran-2,5-diyl.

The invention includes items described below.

Item 1. A compound, represented by formula (1):

wherein, in formula (1),

R¹ and R² are independently hydrogen or alkyl having 1 to 15 carbons,and in the alkyl, at least one piece of —CH₂— may be replaced by —O—,—S—, —CO— or —SiH₂, and at least one piece of —CH₂CH₂— may be replacedby —CH═CH— or —C≡C—, and in the groups, at least one hydrogen may bereplaced by fluorine or chlorine;

A¹, A² and A³ are independently 1,2-cyclopropylene, 1,3-cyclobutylene,1,3-cyclopentylene, 1,4-cyclohexylene, 1,4-cycloheptylene,1,4-phenylene, decahydronaphthalene-2,6-diyl,1,2,3,4-tetrahydronaphthalene-2,6-diyl, naphthalene-2,6-diyl,9,10-dihydrophenanthrene-2,7-diyl, 9H-xanthene-2,6-diyl or9H-fluorene-2,7-diyl, and in the groups, at least one piece of —CH₂— maybe replaced by —O—, —S—, —CO— or —SiH₂—, and at least one piece of—CH₂CH₂— may be replaced by —CH═CH— or —CH═N—, and in the divalentgroups, at least one hydrogen may be replaced by fluorine, chlorine,—C≡N, —CF₃, —CHF₂, —CH₂F, —OCF₃, —OCHF₂ or —OCH₂F;

Z¹, Z² and Z³ are independently a single bond or alkylene having 1 to 6carbons, and in the alkylene, at least one piece of —CH₂— may bereplaced by —O—, —S—, —CO— or —SiH₂—, and one or two pieces of —CH₂CH₂—may be replaced by —CH═CH— or —C≡C—, and in the divalent groups, atleast one hydrogen may be replaced by fluorine or chlorine;

Y¹, Y², Y³ and Y⁴ are independently hydrogen, fluorine, chlorine, —CF³or —CHF², and at least two of Y¹, Y², Y³ and Y⁴ is fluorine, chlorine,—CF₃ or —CHF₂; and a, b and c are independently 0 or 1, and a sum of a,b and c is 0 to 3.

Item 2. The compound according to item 1, wherein, in formula (1), A¹,A² and A³ are independently 1,4-cyclohexylene, 1,4-cycloheptylene,1,4-cyclohexenylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene, tetrahydropyran-2,5-diyl,1,3-dioxane-2,5-diyl, pyridine-2,5-diyl, pyrimidine-2,5-diyl,decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl ornaphthalene-2,6-diyl.

Item 3. The compound according to item 1, wherein, in formula (1), Z¹,Z² and Z³ are independently a single bond, —(CH₂)₂—, —CH═CH—, —C≡C—,—COO—, —OCO—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂— or —CF═CF—.

Item 4. The compound according to any one of items 1 to 3, representedby any one of formulas (1-1) to (1-5):

wherein, in formulas (1-1) to (1-5),

R¹ and R² are independently hydrogen, alkyl having 1 to 10 carbons,alkenyl having 2 to 10 carbons, alkoxy having 1 to 10 carbons oralkenyloxy having 2 to 10 carbons, and in the groups, at least onehydrogen may be replaced by fluorine;

ring A¹, ring A² and ring A³ are independently 1,4-cyclohexylene,1,4-cyclohexenylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene or tetrahydropyran-2,5-diyl;

Z¹, Z² and Z³ are independently a single bond, —(CH₂)₂—, —C≡C—, —CF₂O—,—OCF₂—, —CH₂O— or —OCH₂—; and

Y¹, Y², Y³ and Y⁴ are independently hydrogen, fluorine, chlorine, —CF₃or —CHF₂, and at least two of Y¹, Y², Y³ and Y⁴ is fluorine, chlorine,—CF₃ or —CHF₂.

Item 5. The compound according to item 1, represented by any one offormulas (1-6) to (1-11):

wherein, in formulas (1-6) to (1-11),

R¹ and R² are independently alkyl having 1 to 10 carbons, alkenyl having2 to 10 carbons, alkoxy having 1 to 10 carbons or alkenyloxy having 2 to10 carbons, and in the groups, at least one hydrogen may be replaced byfluorine;

Z¹ is a single bond, —(CH₂)₂—, —CH₂O— or —OCH₂—;

Y¹, Y², Y³ and Y⁴ are independently hydrogen or fluorine, and at leasttwo of Y¹, Y², Y³ and Y⁴ is fluorine; and

L¹ and L² are independently hydrogen or fluorine.

Item 6. The compound according to item 1, represented by any one offormulas (1-12) to (1-14):

wherein, in formulas (1-12) to (1-14),

R¹ and R² are independently alkyl having 1 to 10 carbons, alkenyl having2 to 10 carbons or alkoxy having 1 to 10 carbons;

Z¹ is a single bond, —(CH₂)₂—, —CH₂O— or —OCH₂—;

Y¹, Y², Y³ and Y⁴ are independently hydrogen or fluorine, and at leasttwo of Y¹, Y², Y³ and Y⁴ is fluorine; and

L¹ and L² are independently hydrogen or fluorine.

Item 7. The compound according to item 1, represented by any one offormulas (1-15) to (1-32):

wherein, in formulas (1-15) to formula (1-32),

R¹ and R² are independently alkyl having 1 to 10 carbons, alkenyl having2 to 10 carbons or alkoxy having 1 to 10 carbons; and

L¹ and L² are independently hydrogen or fluorine.

Item 8. The compound according to item 1, represented by any one offormulas (1-33) to (1-36):

wherein, in formulas (1-33) to (1-36),

R¹ and R² are independently alkyl having 1 to 10 carbons or alkoxy 1 to10 carbons.

Item 9. A liquid crystal composition, containing at least one compoundaccording to any one of items 1 to 8.

Item 10. The liquid crystal composition according to item 9, furthercontaining at least one compound selected from the group of compoundsrepresented by formulas (2) to (4):

wherein, in formulas (2) to (4),

R¹¹ and R¹² are independently alkyl having 1 to 10 carbons or alkenylhaving 2 to 10 carbons, and in the alkyl and the alkenyl, at least onepiece of —CH₂— may be replaced by —O—, and in the groups, at least onehydrogen may be replaced by fluorine;

ring B¹, ring B², ring B³ and ring B⁴ are independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,5-difluoro-1,4-phenylene or pyrimidine-2,5-diyl; and Z¹¹, Z¹² and Z¹³are independently a single bond, —COO—, —CH₂CH₂—, —CH═CH— or —C≡C—.

Item 11. The liquid crystal composition according to item 9 or 10,further containing at least one compound selected from the group ofcompounds represented by formulas (5) to (11):

wherein, in formulas (5) to (11),

R¹³, R¹⁴ and R¹⁵ are independently alkyl having 1 to 10 carbons oralkenyl having 2 to 10 carbons, and in the alkyl and the alkenyl, atleast one piece of —CH₂— may be replaced by —O—, and in the groups, atleast one hydrogen may be replaced by fluorine, and R¹⁵ may be hydrogenor fluorine;

ring C¹, ring C², ring C³ and ring C⁴ are independently1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene in which at leastone hydrogen may be replaced by fluorine, tetrahydropyran-2,5-diyl, ordecahydronaphthalene-2,6-diyl;

ring C⁵ and ring C⁶ are independently 1,4-cyclohexylene,1,4-cyclohexenylene, 1,4-phenylene, tetrahydropyran-2,5-diyl ordecahydronaphthalene-2,6-diy;

Z¹⁴, Z^(is), Z¹⁶ and Z¹⁷ are independently a single bond, —COO—, —CH₂O—,—OCF₂—, —CH₂CH₂— or —OCF₂CH₂CH₂—;

L¹¹ and L¹² are independently fluorine or chlorine;

S¹¹ is hydrogen or methyl;

X is —CHF— or —CF₂—; and

j, k, m, n, p, q, r and s are independently 0 or 1, a sum of k, m, n andp is 1 or 2, a sum of q, r and s is 0, 1, 2 or 3, and t is 1, 2 or 3.

Item 12. The liquid crystal composition according to item 8 or 9,further containing at least one compound selected from the group ofcompounds represented by formulas (12) to (14):

wherein, in formulas (12) to (14),

R¹⁶ is alkyl having 1 to 10 carbons or alkenyl having 2 to 10 carbons,and in the alkyl and the alkenyl, at least one piece of —CH₂— may bereplaced by —O—, and in the groups, at least one hydrogen may bereplaced by fluorine;

X¹¹ is fluorine, chlorine, —CF₃, —CHF₂, —CH₂F, —OCF₃, —OCHF₂, —OCF₂CHF₂or —OCF₂CHFCF₃;

ring D¹, ring D² and ring D³ are independently 1,4-cyclohexylene,1,4-phenylene in which at least one hydrogen may be replaced byfluorine, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, orpyrimidine-2,5-diyl;

Z¹⁸, Z¹⁹ and Z²⁰ are independently a single bond, —COO—, —CH₂O—, —CF₂O—,—OCF₂—, —CH₂CH₂—, —CH═CH—, —C≡C— or —(CH₂)₄—; and

L¹³ and L¹⁴ are independently hydrogen or fluorine.

Item 13. The liquid crystal composition according to any one of items 9to 12, further containing at least one compound selected from the groupof compounds represented by formula (15):

wherein, in formula (15),

R¹⁷ is alkyl having 1 to 10 carbons or alkenyl having 2 to 10 carbons,and in the alkyl and the alkenyl, at least one piece of —CH₂— may bereplaced by —O—, and in the groups, at least one hydrogen may bereplaced by fluorine;

X¹² is —C≡N or —C≡C—C≡N;

ring E¹ is 1,4-cyclohexylene, 1,4-phenylene in which at least onehydrogen may be replaced by fluorine, tetrahydropyran-2,5-diyl,1,3-dioxane-2,5-diyl, or pyrimidine-2,5-diyl;

Z²¹ is a single bond, —COO—, —CH₂O—, —CF₂O—, —OCF₂—, —CH₂CH₂— or —C≡C—;

L¹⁵ and L¹⁶ are independently hydrogen or fluorine; and

i is 1, 2, 3 or 4.

Item 14. A liquid crystal display device, including the liquid crystalcomposition according to any one of items 9 to 13.

The invention further includes the following items: (a) the composition,further containing at least one optically active compound and/or atleast one polymerizable compound; and (b) the composition, furthercontaining at least one antioxidant and/or at least one ultravioletlight absorber.

The invention still further includes the following items: (c) thecomposition, further containing one, two or at least three additivesselected from the group of a polymerizable compound, a polymerizationinitiator, a polymerization inhibitor, an optically active compound, anantioxidant, an ultraviolet light absorber, a light stabilizer, a heatstabilizer, a dye and an antifoaming agent; and (d) the composition,wherein a maximum temperature of a nematic phase is 70° C. or higher, anoptical anisotropy (measured at 25° C.) at a wavelength of 589nanometers is 0.08 or more and a dielectric anisotropy (measured at 25°C.) at a frequency of 1 kHz is −2 or less.

The invention still further includes the following items: (e) a deviceincluding the composition and having a PC mode, a TN mode, an STN mode,an ECB mode, an OCB mode, an IPS mode, a VA mode, an FFS mode, an FPAmode or a PSA mode; (f) an AM device including the composition; (g) atransmissive device including the composition; (h) use of thecomposition as the composition having the nematic phase; and (i) use asan optically active composition by adding the optically active compoundto the composition.

An aspect of compound (1), synthesis of compound (1), the liquid crystalcomposition and the liquid crystal display device will be described inthe order.

1. Aspect of Compound (1)

Compound (1) has features of having a fluorodibenzofuran ring. Thecompound is physically and chemically significantly stable underconditions in which the device is ordinarily used, and has large opticalanisotropy, large negative dielectric anisotropy and good compatibilitywith other liquid crystal compounds. A composition containing thecompound is stable under conditions in which the device is ordinarilyused. When the composition is stored at low temperature, the compoundhas small tendency of precipitation as a crystal (or a smectic phase).The compound has general physical properties required for a component ofthe composition, such as large optical anisotropy and large negativedielectric anisotropy.

Preferred examples of terminal groups R¹ and R², A¹, A², A³ and A⁴,bonding groups Z¹, Z², Z³ and Z⁴, lateral groups Y¹, Y² and Y³, and a,b, c and d in compound (1) are as described below. In compound (1),physical properties can be arbitrarily adjusted by suitably combiningthe groups. Compound (1) may contain a larger amount of isotope such as²H (deuterium) and ¹³C than the amount of natural abundance because nosignificant difference exists in the physical properties of thecompound. In addition, definitions of symbols of compound (1) are asdescribed in item 1.

In formula (1), R¹ and R² are independently hydrogen or alkyl having 1to 15 carbons, and in the alkyl, at least one piece of —CH₂— may bereplaced by —O—, —S—, —CO— or —SiH₂—, and at least one piece of —CH₂CH₂—may be replaced by —CH═CH— or —C≡C—, and in the groups, at least onehydrogen may be replaced by fluorine or chlorine.

Preferred R¹ or R² is hydrogen, alkyl, alkoxy, alkoxyalkyl,alkoxyalkoxy, alkylthio, alkylthioalkoxy, acyl, acylalkyl, acyloxy,acyloxyalkyl, alkoxycarbonyl, alkoxycarbonylalkyl, alkenyl, alkenyloxy,alkenyloxyalkyl, alkoxyalkenyl, alkynyl, alkynyloxy, silaalkyl anddisilaalkyl. In the groups, at least one hydrogen may be replaced byfluorine or chlorine. The example includes a group in which at least twohydrogens are replaced by both fluorine and chlorine. A group in whichat least one hydrogen is replaced by fluorine only is further preferred.In the groups, a straight chain is preferred to a branched chain.However, if R¹ or R² has the branched chain, the group is preferred whenthe group has optical activity. Further preferred R¹ or R² is alkyl,alkoxy, alkoxyalkyl, alkenyl, monofluoroalkyl, polyfluoroalkyl,monofluoroalkoxy, polyfluoroalkoxy, monofluoroalkenyl andpolyfluoroalkenyl.

A preferred configuration of —CH═CH— in the alkenyl depends on aposition of a double bond. A trans configuration is preferred in thealkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyland 3-hexenyl. A cis configuration is preferred in the alkenyl such as2-butenyl, 2-pentenyl and 2-hexenyl.

Specific R¹ or R² is hydrogen, methyl, ethyl, propyl, butyl, pentyl,hexyl, heptyl, octyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy, heptyloxy, methoxymethyl, methoxyethyl, methoxypropyl,ethoxymethyl, ethoxyethyl, ethoxypropyl, propoxymethyl, butoxymethyl,pentoxymethyl, vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl,3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,2-propenyloxy, 2-butenyloxy, 2-pentenyloxy, 1-propynyl and 1-pentenyl.

Specific R¹ or R² is 2-fluoroethyl, 3-fluoropropyl,2,2,2-trifluoroethyl, 2-fluorovinyl, 2,2-difluorovinyl,2-fluoro-2-vinyl, 3-fluoro-1-propenyl, 3,3,3-trifluoro-1-propenyl,4-fluoro-1-propenyl and 4,4-difluoro-3-butenyl.

Further preferred R¹ or R² is methyl, ethyl, propyl, butyl, pentyl,hexyl, heptyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy,methoxymethyl, ethoxymethyl, propoxymethyl, vinyl, 1-propenyl,2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl,3-pentenyl, 4-pentenyl, 2-propenyloxy, 2-butenyloxy and 2-pentenyloxy.Most preferred R or R² is methyl, ethyl, propyl, butyl, pentyl, methoxy,ethoxy, propoxy, butoxy, pentyloxy, vinyl, 1-propenyl, 3-butenyl and3-pentenyl.

In formula (1), A¹, A² and A³ are independently 1,2-cyclopropylene,1,3-cyclobutylene, 1,3-cyclopentylene, 1,4-cyclohexylene,1,4-cycloheptylene, 1,4-phenylene, decahydronaphthalene-2,6-diyl,1,2,3,4-tetrahydronaphthalene-2,6-diyl, naphthalene-2,6-diyl,9,10-dihydrophenanthrene-2,7-diyl, 9H-xanthene-2,6-diyl or9H-fluorene-2,7-diyl, and in the groups, at least one piece of —CH₂— maybe replaced by —O—, —S—, —CO— or —SiH₂—, and at least one piece of—CH₂CH₂— may be replaced by —CH═CH— or —CH═N—, and in the divalentgroups, at least one hydrogen may be replaced by fluorine, chlorine,—C≡N, —CF₃, —CHF₂, —CH₂F, —OCF₃, —OCHF₂ or —OCH₂F.

Preferred examples of “in the groups, at least one piece of —CH₂— may bereplaced by —O—, —S—, —CO— or —SiH₂—, and at least one piece of —CH₂CH₂—may be replaced by —CH═CH— or —CH═N—” include a divalent grouprepresented by formulas (16-1) to (16-50) described below. Furtherpreferred examples include the divalent group represented by formulas(16-1) to (16-4), formula (16-15), formula (16-23), formulas (16-27) to(16-29), formula (16-36), formula (16-39) and formula (16-45).

Preferred examples of “in the divalent groups, at least one hydrogen maybe replaced by fluorine, chlorine, —C≡N, —CF₃, —CHF₂, —CH₂F, —OCF₃,—OCHF₂ or —OCH₂F” include a divalent group represented by formulas(17-1) to (17-77) each described below. Further preferred examplesinclude the divalent group represented by formulas (17-1) to (17-4),formula (17-6), formulas (17-10) to (17-15), formulas (17-54) to (17-59)and formulas (17-72) to (17-76).

Further preferred A¹, A² or A³ is 1,4-cyclohexylene,1,4-cyclohexenylene, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl,1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene,2,5-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene,2,3,5-trifluoro-1,4-phenylene, pyridine-2,5-diyl,3-fluoropyridine-2,5-diyl, pyrimidine-2,5-diyl, pyridazine-2,5-diyl,decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyland naphthalene-2,6-diyl. With regard to a configuration of1,4-cyclohexylene, tetrahydropyran-2,5-diyl and 1,3-dioxane-2,5-diyl,trans is preferred to cis.

Particularly preferred A¹, A² or A³ is 1,4-cyclohexylene,1,4-cyclohexenylene, tetrahydropyran-2,5-diyl, 1,4-phenylene,2-fluoro-1,4-phenylene and 2,3-difluoro-1,4-phenylene. Most preferredA¹, A² or A³ is 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenyleneand 2,3-difluoro-1,4-phenylene.

In formula (1), Z¹, Z² and Z³ are independently a single bond oralkylene having 1 to 6 carbons, and in the alkylene, at least one pieceof —CH₂— may be replaced by —O—, —S—, —CO— or —SiH₂—, and one or twopieces of —CH₂CH₂— may be replaced by —CH═CH— or —C≡C—, and in thedivalent groups, at least one hydrogen may be replaced by fluorine orchlorine.

Specific examples of Z¹, Z² or Z³ include a single bond, —COO—, —OCO—,—CH₂O—, —OCH₂—, —CF₂O—, —OCF₂—, —CH₂CH₂—, —CH═CH—, —CF═CH—, —CH═CF—,—CF═CF—, —C≡C—, —CH₂CO—, —COCH₂—, —CH₂SiH₂—, —SiH₂CH₂—, —(CH₂)₄—,—(CH₂)₂COO—, —(CH₂)₂OCO—, —OCO(CH₂)₂—, —COO(CH₂)₂—, —(CH₂)₂CF₂O—,—(CH₂)₂OCF₂—, —OCF₂ (CH₂)₂—, —CF₂O(CH₂)₂—(CH₂)₃O— or —O(CH₂)₃—. Withregard to a configuration of a double bond of a bonding group such as—CH═CH—, —CF═CF—, —CH═CH—CH₂O— and —OCH₂—CH═CH—, trans is preferred tocis.

Preferred Z¹, Z² or Z³ is a single bond, —(CH₂)₂—, —CH═CH—, —C≡C—,—COO—, —OCO—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂— and —CF═CF—. Furtherpreferred Z₁, Z₂ or Z₃ is a single bond, —(CH₂)₂—, —CH═CH—, —C≡C—,—CH₂O—, and —OCH₂—. Most preferred Z¹, Z² or Z³ is a single bond,—(CH₂)₂—, —CH₂O— and —OCH₂—.

In formula (1), Y¹, Y², Y³ and Y⁴ are independently fluorine, chlorine,—CF₃ or —CHF₂. Preferred Y¹, Y², Y³ and Y⁴ are fluorine.

In formula (1), a, b and c are independently 0 or 1, and a sum of a, band c is 0 to 3. Compound (1) has zero to three rings in addition to thefluorodibenzofuran ring. The rings also include a fused ring or abridged six-membered ring in addition to an ordinary six-membered ring.

Physical properties such as optical anisotropy and dielectric anisotropycan be arbitrarily adjusted by suitably selecting a terminal group, aring and a bonding group in compound (1). An effect of kinds of terminalgroups R¹ and R², rings A¹, A² and A³ and bonding groups Z¹, Z² and Z³on physical properties of compound (1) will be described below.

In compound (1), when R¹ or R² has the straight chain, a temperaturerange of the liquid crystal phase is wide, and the viscosity is small.When R¹ or R² has the branched chain, the compatibility with otherliquid crystal compounds is good. A compound in which R¹ or R² is anoptically active group is useful as a chiral dopant. A reverse twisteddomain to be generated in the device can be prevented by adding thecompound to the composition. A compound in which R¹ or R² is not theoptically active group is useful as a component of the composition. WhenR¹ or R² is alkenyl, a preferred configuration depends on a position ofa double bond. An alkenyl compound having the preferred configurationhas high maximum temperature or a wide temperature range of the liquidcrystal phase. A detailed description is found in Mol. Cryst. Liq.Cryst., 1985, 131, 109 and Mol. Cryst. Liq. Cryst., 1985, 131, 327.

When ring A¹, A² or A³ is 1,4-phenylene in which at least one hydrogenmay be replaced by fluorine or chlorine, pyridine-2,5-diyl,pyrimidine-2,5-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl,naphthalene-2,6-diyl, 9,10-dihydrophenanthrene-2,7-diyl,9H-xanthene-2,6-diyl or 9H-fluorene-2,7-diyl, the optical anisotropy islarge. When ring A¹, A² or A³ is 1,4-cyclohexylene, 1,4-cyclohexenylene,decahydronaphthalene-2,6-diyl, tetrahydropyran-2,5-diyl or1,3-dioxane-2,5-diyl, the optical anisotropy is small. When ring A¹, A²or A³ is 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene ortetrahydropyran-2,5-diyl, the dielectric anisotropy is negatively large.When ring A¹, A² or A³ is 1,4-cyclohexenylene, 2-fluoro-1,4-phenylene ortetrahydropyran-2,5-diyl, the compatibility with other liquid crystalcompounds is good.

When at least two rings are 1,4-cyclohexylene, the maximum temperatureis high, the optical anisotropy is small, and the viscosity is small.When at least one ring is 1,4-phenylene, the optical anisotropy iscomparatively large and an orientational order parameter is large. Whenat least two rings are 1,4-phenylene, the optical anisotropy is large,the temperature range of the liquid crystal phase is wide, and themaximum temperature is high.

When bonding group Z¹, Z² or Z³ is a single bond, —(CH₂)₂—, —CH═CH—,—CF₂O—, —OCF₂—, —CH₂O—, —OCH₂— or —CF═CF—, the viscosity is small. Whenthe bonding group is a single bond, —CH₂CH₂—, —CH═CH—, —OCF₂— or —CF₂O—,the viscosity is further smaller. When the bonding group is —(CH₂)₂—,—CH═CH—, —CH₂O— or —OCH₂—, the temperature range of the liquid crystalphase is wide, and an elastic constant ratio K₃₃/K₁₁ (K₃₃: a bendelastic constant, K₁₁: a splay elastic constant) is large. When thebonding group is —C≡C—, the optical anisotropy is large.

When Y¹, Y², Y³ or Y⁴ is composed of hydrogen and fluorine, the clearingpoint is high and the compatibility with other liquid crystal compoundsis good. When Y¹, Y², Y³ or Y⁴ consists essentially of fluorine, theclearing point is high, the dielectric anisotropy is negatively largeand the viscosity is small. When Y¹, Y², Y³ or Y⁴ is composed offluorine and —CF₃, the dielectric anisotropy is negatively large andchemical stability is high. When at least one of Y¹, Y², Y³ or Y⁴ is—OCF₃, —OCHF₂ or —OCH₂F, the compatibility with other liquid crystalcompounds is good.

When compound (1) consists essentially of the fluorodibenzofuran ring,the viscosity is small. When compound (1) has one ring in addition tothe fluorodibenzofuran ring, the clearing point is high, the viscosityis small and the compatibility with other liquid crystal compounds isgood. When compound (1) has two or three rings in addition to thefluorodibenzofuran ring, the clearing point is particularly high. Asdescribed above, a compound having required physical properties can beobtained by suitably selecting a kind of the terminal group, the ringand the bonding group, and the number of the rings. Accordingly,compound (1) is useful as a component of a composition used in a devicehaving a mode such as the PC mode, the TN mode, the STN mode, the ECBmode, the OCB mode, the IPS mode and the VA mode.

Preferred examples of compound (1) include compound (1-6) to compound(1-11) described in item 5. Further preferred examples include compound(1-12) to compound (1-14) described in item 6. Still further preferredexamples include compound (1-15) to compound (1-32) described in item 7.Most preferred examples include compound (1-33) to compound (1-36)described in item 8. Compound (1) is suitable for a device having a modesuch as the VA mode, the IPS mode and the PSA mode.

2. Synthesis of Compound (1)

A synthetic method of compound (1) will be described. Compound (1) canbe prepared by suitably combining methods in synthetic organicchemistry. A method for introducing a required terminal group, ring andbonding group into a starting material is described in books such as“Organic Syntheses” (John Wiley & Sons, Inc.), “Organic Reactions” (JohnWiley & Sons, Inc.), “Comprehensive Organic Synthesis” (Pergamon Press)and “New Experimental Chemistry Course (Shin Jikken Kagaku Koza inJapanese)” (Maruzen Co., Ltd.).

2-1. Formation of Bonding Group Z

First, a scheme is shown with regard to a method for forming bondinggroups Z¹ to Z³. Next, reactions described in the scheme in methods (1)to (11) will be described. In the scheme, MSG¹ (or MSG²) is a monovalentorganic group having at least one ring. The monovalent organic groupsrepresented by a plurality of MSG¹ (or MSG²) used in the scheme may beidentical or different. Compounds (1A) to (1J) correspond to compound(1).

(1) Formation of a Single Bond

Compound (1A) is prepared by allowing aryl boronic acid (21) preparedaccording to a publicly known method to react with halide (22), in thepresence of carbonate and a catalyst such astetrakis(triphenylphosphine)palladium. Compound (1A) is also prepared byallowing halide (23) prepared according to a publicly known method toreact with n-butyllithium and subsequently with zinc chloride, andfurther with halide (22) in the presence of a catalyst such asdichlorobis(triphenylphosphine)palladium.

(2) Formation of —COO—

Carboxylic acid (24) is obtained by allowing halide (23) to react withn-butyllithium and subsequently with carbon dioxide. Compound (1B) isprepared by dehydration of compound (25) prepared according to apublicly known method and carboxylic acid (24) in the presence of1,3-dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP).

(3) Formation of —CF₂O—

Thionoester (26) is obtained by treating compound (1B) with a thiationreagent such as Lawesson's reagent. Compound (1C) is prepared byfluorinating thionoester (26) with a hydrogen fluoride-pyridine complexand N-bromosuccinimide (NBS). Refer to M. Kuroboshi et al., Chem. Lett.,1992, 827. Compound (1C) is also prepared by fluorinating thionoester(26) with (diethylamino) sulfur trifluoride (DAST). Refer to W. H.Bunnelle et al., J. Org. Chem. 1990, 55, 768. The bonding group can alsobe formed according to the method described in Peer. Kirsch et al.,Angew. Chem. Int. Ed. 2001, 40, 1480.

(4) Formation of —CH═CH—

Aldehyde (28) is obtained by treating halide (22) with n-butyllithiumand then allowing the treated halide to react with N,N-dimethylformamide(DMF). Phosphorus ylide is generated by treating phosphonium salt (27)prepared according to a publicly known method with a base such aspotassium t-butoxide. Compound (1D) is prepared by allowing thephosphorus ylide to react with aldehyde (28). A cis isomer may begenerated depending on reaction conditions, and therefore the cis isomeris isomerized into a trans isomer according to a publicly known methodwhen necessary.

(5) Formation of —(CH₂)₂—

Compound (1E) is prepared by hydrogenating compound (1D) in the presenceof a catalyst such as palladium on carbon.

(6) Formation of —(CH₂)₄—

A compound having —(CH₂)₂—CH═CH— is obtained by using phosphonium salt(29) in place of phosphonium salt (27) according to the method in method(4). Compound (1F) is prepared by performing catalytic hydrogenation ofthe compound obtained.

(7) Formation of —CH₂CH═CHCH₂—

Compound (1G) is prepared by using phosphonium salt (30) in place ofphosphonium salt (27) and aldehyde (31) in place of aldehyde (28)according to the method of method (4). A trans isomer may be generateddepending on reaction conditions, and therefore the trans isomer isisomerized to a cis isomer according to a publicly known method whennecessary.

(8) Formation of —C≡C—

Compound (32) is obtained by allowing halide (23) to react with2-methyl-3-butyn-2-ol in the presence of a catalyst of dichloropalladiumand copper halide, and then performing deprotection under basicconditions. Compound (1H) is prepared by allowing compound (32) to reactwith halide (22) in the presence of the catalyst of dichloropalladiumand copper halide.

(9) Formation of —CF═CF—

Compound (33) is obtained by treating halide (23) with n-butyllithiumand then allowing the treated halide to react with tetrafluoroethylene.Compound (1I) is prepared by treating halide (22) with n-butyllithium,and then allowing the treated halide to react with compound (33).

(10) Formation of —OCH₂—

Compound (34) is obtained by reducing aldehyde (28) with a reducingagent such as sodium borohydride. Bromide (35) is obtained bybrominating compound (34) with hydrobromic acid or the like. Compound(1J) is prepared by allowing bromide (35) to react with compound (36) inthe presence of a base such as potassium carbonate.

(11) Formation of —(CF₂)₂—

A compound having —(CF₂)₂— is obtained by fluorinating diketone (—COCO—)with sulfur tetrafluoride, in the presence of a hydrogen fluoridecatalyst, according to a method described in J. Am. Chem. Soc., 2001,123, 5414.

2-2. Formation of Rings A¹ to A³

Next, a formation method with regard to rings A¹ to A³ will bedescribed. A starting material is commercially available or theformation method is well known with regard to a ring such as1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, 1,4-phenylene,2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, pyridine-2,5-diyland pyrimidine-2,5-diyl. Then, compounds (64), (67) and (71) describedbelow will be described.

Decahydronaphthalene-2,6-dione (64) is a starting material of a compoundhaving decahydronaphthalene-2,6-diyl. The compound (64) is obtained byperforming catalytic hydrogenation with diol (63) in the presence ofruthenium oxide according to a method described in JP 2000-239564 A, andfurther oxidizing the resulting material with chromium oxide. Thecompound obtained is converted into compound (1) according to anordinary method.

A structural unit of 2,3-(bistrifluoromethyl)phenylene is preparedaccording to a method described in Org. Lett., 2000, 2 (21), 3345.Aniline (66) is prepared by allowing furan (65) to perform Diels Alderreaction with 1,1,1,4,4,4-hexafluoro-2-butyne at high temperature.Iodide (67) is obtained by performing a Sandmeyer reaction to thecompound obtained according to a method described in Org. Synth. Coll.,Vol. 2, 1943, 355. The compound obtained is converted into compound (1)according to an ordinary method.

A structural unit of 2-difluoromethyl-3-fluorophenylene is preparedaccording to a method as described below. Compound (69) is obtained byprotecting a hydroxyl group of compound (68) with a suitable protectivegroup. P means the protective group. Aldehyde (70) is obtained byallowing s-butyllithium to act on compound (69), and subsequentlyallowing the obtained material to react with N,N-dimethylformamide(DMF). Phenol (71) is obtained by fluorinating the compound obtainedwith diethylaminosulfur trifluoride (DAST), and subsequentlydeprotecting the resulting material. The compound obtained is convertedinto compound (1) according to an ordinary method.

2-3. Synthesis Example

An example of a method for preparing compound (1) is as described below.In the compounds, R¹, R², A¹, A², A³, Z¹, Z², Z³, Y¹, Y², Y³, Y⁴, a, band c are defined in a manner identical with the definitions in item 1.

An example of a method for preparing compound (1) is as described below.Compound (43) is obtained by sequentially adding copper(I) chloride,cesium carbonate and 2,2,6,6-tetramethylheptane-3,5-dione to compound(41) and compound (42) prepared according to a publicly known method,and the resulting material was stirred and heated. Next, compound (1)can be prepared by allowing n-butyllithium to act on compound (43), andthen adding iron(III) chloride thereto.

3. Liquid Crystal Composition 3-1. Component Compound

A liquid crystal composition of the invention will be described. Thecomposition contains at least one compound (1) as component (a). Thecomposition may contain two, three or more compounds (1). A component inthe composition may be only compound (1). The composition preferablycontains at least one of compounds (1) in a range of about 1% by weightto about 99% by weight in order to develop good physical properties. Ina composition having negative dielectric anisotropy, a preferred contentof compound (1) is in a range of about 5% by weight to about 60% byweight. In a composition having positive dielectric anisotropy, apreferred content of compound (1) is about 30% by weight or less.

TABLE 1 Component compound of composition Dielectric Component Componentcompound anisotropy Component (a) Compound (1) Negatively largeComponent (b) Compound (2) to compound (4) Small Component (c) Compound(5) to compound (11) Negatively large Component (d) Compound (12) tocompound (14) Positively large Component (e) Compound (15) Positivelylarge

The composition contains compound (1) as component (a). The compositionfurther preferably contains a liquid crystal compound selected fromcomponents (b) to (e) described in Table 1. When the composition isprepared, components (b) to (e) are preferably selected by taking intoaccount the positive or negative dielectric anisotropy and magnitude ofthe dielectric anisotropy. The composition may contain a liquid crystalcompound different from compounds (1) to (15). The composition may notcontain such a liquid crystal compound.

Component (b) includes a compound in which two terminal groups are alkylor the like. Specific examples of preferred component (b) includecompounds (2-1) to (2-11), compounds (3-1) to (3-19) and compounds (4-1)to (4-7). In the compounds, R¹¹ and R¹² are independently alkyl having 1to 10 carbons or alkenyl having 2 to 10 carbons, and in the alkyl andthe alkenyl, at least one piece of —CH₂— may be replaced by —O—, and inthe groups, at least one hydrogen may be replaced by fluorine.

Component (b) has small dielectric anisotropy. Component (b) is close toneutrality. Compound (2) is effective in decreasing the viscosity oradjusting the optical anisotropy. Compounds (3) and (4) are effective inextending the temperature range of the nematic phase by increasing themaximum temperature, or in adjusting the optical anisotropy.

As a content of component (b) is increased, the viscosity of thecomposition is decreased, but the dielectric anisotropy is decreased.Thus, as long as a desired value of threshold voltage of a device ismet, the content is preferably as large as possible. When a compositionfor the IPS mode, the VA mode or the like is prepared, the content ofcomponent (b) is preferably about 30% by weight or more, and furtherpreferably about 40% by weight or more, based on the weight of theliquid crystal composition.

Component (c) includes compounds (5) to (11). The compounds havephenylene in which hydrogen in lateral positions are replaced by twohalogens, such as 2,3-difluoro-1,4-phenylene. Specific examples ofpreferred component (c) include compounds (5-1) to (5-8), compounds(6-1) to (6-18), compound (7-1), compounds (8-1) to (8-3), compounds(9-1) to (9-11), compounds (10-1) to (10-3) and compounds (11-1) to(11-3). In the compounds, R¹³, R¹⁴ and R¹⁵ are independently alkylhaving 1 to 10 carbons or alkenyl having 2 to 10 carbons, and in thealkyl and the alkenyl, at least one piece of —CH₂— may be replaced by—O—, and in the groups, at least one hydrogen may be replaced byfluorine, and R¹⁵ may be hydrogen or fluorine.

Component (c) has negatively large dielectric anisotropy. Component (c)is used when a composition for the IPS mode, the VA mode, the PSA modeor the like is prepared. As a content of component (c) is increased, thedielectric anisotropy of the composition is negatively increased, butthe viscosity is increased. Thus, as long as a desired value ofthreshold voltage of the device is met, the content is preferably assmall as possible. When the dielectric anisotropy at a degree of −5 istaken into account, the content is preferably about 40% by weight ormore in order to allow a sufficient voltage driving.

Among types of component (c), compound (5) is a bicyclic compound, andtherefore is effective in decreasing the viscosity, adjusting theoptical anisotropy or increasing the dielectric anisotropy. Compounds(5) and (6) are a tricyclic compound, and therefore are effective inincreasing the maximum temperature, the optical anisotropy or thedielectric anisotropy. Compounds (8) to (11) are effective in increasingthe dielectric anisotropy.

When a composition for the IPS mode, the VA mode, the PSA mode or thelike is prepared, the content of component (c) is preferably about 40%by weight or more, and further preferably in the range of about 50% byweight to about 95% by weight, based on the weight of the liquid crystalcomposition. When component (c) is added to the composition havingpositive dielectric anisotropy, the content of component (c) ispreferably about 30% by weight or less. Addition of component (c) allowsadjustment of the elastic constant of the composition and adjustment ofa voltage-transmittance curve of the device.

Component (d) is a compound having a halogen-containing group or afluorine-containing group at a right terminal. Specific examples ofpreferred component (d) include compounds (12-1) to (12-16), compounds(13-1) to (13-113) and compounds (14-1) to (14-58). In the compounds,R¹⁶ is alkyl having 1 to 10 carbons or alkenyl having 2 to 10 carbons,and in the alkyl and the alkenyl, at least one piece of —CH₂— may bereplaced by —O—, and in the groups, at least one hydrogen may bereplaced by fluorine. X¹¹ is fluorine, chlorine, —OCF₃, —OCHF₂, —CF₃,—CHF₂, —CH₂F, —OCF₂CHF₂ or —OCF₂CHFCF₃.

Component (d) has positive dielectric anisotropy, and significantlysatisfactory stability to heat or light, and therefore is used when acomposition for the IPS mode, the FFS mode, the OCB mode or the like isprepared. A content of component (d) is suitably in the range of about1% by weight to about 99% by weight, preferably in the range of about10% by weight to about 97% by weight, and further preferably in therange of about 40% by weight to about 95% by weight, based on the weightof the liquid crystal composition. When component (d) is added to thecomposition having negative dielectric anisotropy, the content ofcomponent (d) is preferably about 30% by weight or less. Addition ofcomponent (d) allows adjustment of the elastic constant of thecomposition and adjustment of the voltage-transmittance curve of thedevice.

Component (e) is compound (15) in which a right-terminal group is —C≡Nor —C≡C—C≡N. Specific examples of preferred component (e) includecompounds (15-1) to (15-64). In the compounds, R¹⁷ is alkyl having 1 to10 carbons or alkenyl having 2 to 10 carbons, and in the alkyl and thealkenyl, at least one piece of —CH₂— may be replaced by —O—, and in thegroups, at least one hydrogen may be replaced by fluorine. X¹² is —C≡Nor —C≡C—C≡N.

Component (e) has positive dielectric anisotropy and a value thereof islarge, and therefore component (e) is used when a composition for the TNmode or the like is prepared. Addition of component (e) can increase thedielectric anisotropy of the composition. Component (e) is effective inextending the temperature range of the liquid crystal phase, adjustingthe viscosity or adjusting the optical anisotropy. Component (e) is alsouseful for adjustment of the voltage-transmittance curve of the device.

When the composition for the TN mode or the like is prepared, a contentof component (e) is suitably in the range of about 1% by weight to about99% by weight, preferably in the range of about 10% by weight to about97% by weight, and further preferably in the range of about 40% byweight to about 95% by weight, based on the weight of the liquid crystalcomposition. When component (e) is added to a composition havingnegative dielectric anisotropy, the content of component (e) ispreferably about 30% by weight or less. Addition of component (e) allowsadjustment of the elastic constant of the composition and adjustment ofthe voltage-transmittance curve of the device.

A liquid crystal composition satisfying at least one of physicalproperties such as high stability to heat or light, high maximumtemperature, low minimum temperature, small viscosity, suitable opticalanisotropy (more specifically, large optical anisotropy or small opticalanisotropy), large positive or negative dielectric anisotropy, largespecific resistance and a suitable elastic constant (more specifically,a large elastic constant or a small elastic constant) can be prepared bycombining a compound suitably selected from components (b) to (e)described above with compound (1). A device including such a compositionhas a wide temperature range in which the device can be used, a shortresponse time, a large voltage holding ratio, low threshold voltage, alarge contrast ratio, a small flicker rate and a long service life.

If the device is used for a long period of time, a flicker may beoccasionally generated on a display screen. The flicker rate (%) can berepresented by a formula (luminance when applying positivevoltage−luminance when applying negative voltage|/averageluminance)×100. In a device having the flicker rate in the range ofabout 0% to about 1%, a flicker is hardly generated on the displayscreen even if the device is used for a long period of time. The flickeris associated with image persistence, and is presumed to be generatedaccording to a difference in electric potential between a positive frameand a negative frame in driving at alternating current. The compositioncontaining compound (1) is also useful for a decrease in generation ofthe flicker.

3-2. Additive

A liquid crystal composition is prepared according to a publicly knownmethod. For example, the component compounds are mixed and dissolved ineach other by heating. According to an application, an additive may beadded to the composition. Specific examples of the additives include thepolymerizable compound, the polymerization initiator, the polymerizationinhibitor, the optically active compound, the antioxidant, theultraviolet light absorber, the light stabilizer, the heat stabilizer,the dye and the antifoaming agent. Such additives are well known tothose skilled in the art, and described in literature.

In a liquid crystal display device having the polymer sustainedalignment (PSA) mode, the composition contains a polymer. Thepolymerizable compound is added for the purpose of forming the polymerin the composition. The polymerizable compound is polymerized byirradiation with ultraviolet light while voltage is applied betweenelectrodes, and thus the polymer is formed in the composition. Asuitable pretilt is achieved by the method, and therefore the device inwhich a response time is shortened and the image persistence is improvedis prepared.

Preferred examples of the polymerizable compound include acrylate,methacrylate, a vinyl compound, a vinyloxy compound, propenyl ether, anepoxy compound (oxirane, oxetane) and vinyl ketone. Further preferredexamples include a compound having at least one acryloyloxy, and acompound having at least one methacryloyloxy. Still further preferredexamples also include a compound having both acryloyloxy andmethacryloyloxy.

Still further preferred examples include compounds (M-1) to (M-18). Inthe compounds, R²⁵ to R³¹ are independently hydrogen or methyl; R³², R³³and R³⁴ are independently hydrogen or alkyl having 1 to 5 carbons, andat least one of R³², R³³ and R³⁴ is alkyl having 1 to 5 carbons; v, wand x are independently 0 or 1; and u and y are independently an integerfrom 1 to 10. L²¹ to L²⁶ are independently hydrogen or fluorine; and L²⁷and L²⁸ are independently hydrogen, fluorine or methyl.

The polymerizable compound can be rapidly polymerized by adding thepolymerization initiator. An amount of a remaining polymerizablecompound can be reduced by optimizing reaction conditions. Examples of aphotoradical polymerization initiator include TPO, 1173 and 4265 fromDarocur series of BASF SE, and 184, 369, 500, 651, 784, 819, 907, 1300,1700, 1800, 1850 and 2959 from Irgacure series thereof.

Additional examples of the photoradical polymerization initiator include4-methoxyphenyl-2,4-bis(trichloromethyl)triazine,2-(4-butoxystyryl)-5-trichloromethyl-1,3,4-oxadiazole, 9-phenylacridine,9,10-benzphenazine, a benzophenone-Michler's ketone mixture, ahexaarylbiimidazole-mercaptobenzimidazole mixture,1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, benzyl dimethylketal, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one, amixture of 2,4-diethylxanthone and methyl p-dimethylaminobenzoate, and amixture of benzophenone and methyltriethanolamine.

After the photoradical polymerization initiator is added to the liquidcrystal composition, polymerization can be performed by irradiation withultraviolet light while an electric field is applied. However, anunreacted polymerization initiator or a decomposition product of thepolymerization initiator may cause poor display such as imagepersistence in the device. In order to prevent such an event,photopolymerization may be performed with no addition of thepolymerization initiator. A preferred wavelength of irradiation light isin the range of about 150 nanometers to about 500 nanometers. A furtherpreferred wavelength is in the range of about 250 nanometers to about450 nanometers, and a most preferred wavelength is in the range of about300 nanometers to about 400 nanometers.

Upon storing the polymerizable compound, the polymerization inhibitormay be added thereto for preventing polymerization. The polymerizablecompound is ordinarily added to the composition without removing thepolymerization inhibitor. Examples of the polymerization inhibitorinclude hydroquinone, a hydroquinone derivative such asmethylhydroquinone, 4-t-butylcatechol, 4-methoxyphenol andphenothiazine.

The optically active compound is effective in inducing helical structurein liquid crystal molecules to give a required twist angle, and therebypreventing a reverse twist. A helical pitch can be adjusted by addingthe optically active compound thereto. Two or more optically activecompounds may be added for the purpose of adjusting temperaturedependence of the helical pitch. Specific examples of a preferredoptically active compound include compounds (Op-1) to (Op-18) describedbelow. In compound (Op-18), ring J is 1,4-cyclohexylene or1,4-phenylene, and R²⁸ is alkyl having 1 to 10 carbons. Asterisk mark(*) represents asymmetrical carbon.

The antioxidant is effective for maintaining the large voltage holdingratio. Specific examples of a preferred antioxidant include compounds(AO-1) and (AO-2) described below; and Irganox 415, Irganox 565, Irganox1010, Irganox 1035, Irganox 3114 and Irganox 1098 (trade names; BASFSE). The ultraviolet light absorber is effective for preventing adecrease of the maximum temperature. Preferred examples of theultraviolet light absorber include a benzophenone derivative, a benzoatederivative and a triazole derivative, and specific examples includecompounds (AO-3) and (AO-4) described below; Tinuvin 329, Tinuvin P,Tinuvin 326, Tinuvin 234, Tinuvin 213, Tinuvin 400, Tinuvin 328 andTinuvin 99-2 (trade names; BASF SE); and 1,4-diazabicyclo[2.2.2]octane(DABCO).

The light stabilizer such as an amine having steric hindrance ispreferred for maintaining the large voltage holding ratio. Specificexamples of a preferred light stabilizer include compounds (AO-5),(AO-6) and (AO-7) described below; Tinuvin 144, Tinuvin 765 and Tinuvin770DF (trade names; BASF SE); and LA-77Y and LA-77G (trade names; ADEKACorporation). The heat stabilizer is also effective for maintaining thelarge voltage holding ratio, and specific preferred examples includeIrgafos 168 (trade name; BASF SE). A dichroic dye such as an azo dye oran anthraquinone dye is added to the composition to be adapted for adevice having a guest host (GH) mode. The antifoaming agent is effectivefor preventing foam formation. Preferred examples of the antifoamingagent include dimethyl silicone oil and methylphenyl silicone oil.

In compound (AO-1), R⁴⁰ is alkyl having 1 to 20 carbons, alkoxy having 1to 20 carbons, —COOR⁴¹ or —CH₂CH₂COOR⁴¹, in which R⁴¹ is alkyl having 1to 20 carbons. In compounds (AO-2) and (AO-5), R⁴² is alkyl having 1 to20 carbons. In compound (AO-5), R⁴³ is hydrogen, methyl or O. (oxygenradical); and ring G¹ is 1,4-cyclohexylene or 1,4-phenylene; in compound(AO-7), ring G² is 1,4-cyclohexylene, 1,4-phenylene, or 1,4-phenylene inwhich at least one hydrogen is replaced by fluorine; and in compounds(AO-5) and (AO-7), z is 1, 2 or 3.

4. Liquid Crystal Display Device

The liquid crystal composition can be used in a liquid crystal displaydevice having an operating mode such as the PC mode, the TN mode, theSTN mode, the OCB mode and the PSA mode, and driven by an active matrixmode. The composition can also be used in a liquid crystal displaydevice having the operating mode such as the PC mode, the TN mode, theSTN mode, the OCB mode, the VA mode and the IPS mode, and driven by apassive matrix mode. The devices can be applied to any of a reflectivetype, a transmissive type and a transflective type.

The composition is also suitable for a nematic curvilinear aligned phase(NCAP) device, and the composition is microencapsulated herein. Thecomposition can also be used in a polymer dispersed liquid crystaldisplay device (PDLCD) or a polymer network liquid crystal displaydevice (PNLCD). In the compositions, a large amount of polymerizablecompound is added. On the other hand, when a proportion of thepolymerizable compound is about 10% by weight or less based on theweight of the liquid crystal composition, the liquid crystal displaydevice having the PSA mode is prepared. A preferred proportion is in therange of about 0.1% by weight to about 2% by weight based thereon. Afurther preferred proportion is in the range of about 0.2% by weight toabout 1.0% by weight based thereon. The device having the PSA mode canbe driven by the driving mode such as the active matrix mode and thepassive matrix mode. Such devices can be applied to any of thereflective type, the transmissive type and the transflective type.

EXAMPLES 1. Example of Compound (1)

The invention will be described in greater detail by way of Examples.The Examples include a typical example, and therefore the invention isnot limited by the Examples. Compound (1) was prepared according toprocedures described below. The thus prepared compound was identified bymethods such as an NMR analysis. Physical properties of the compound andthe composition, and characteristics of a device were measured bymethods described below.

NMR analysis: For measurement, DRX-500 made by Bruker BioSpinCorporation was used. In ¹H-NMR measurement, a sample was dissolved in adeuterated solvent such as CDCl₃, and measurement was carried out underconditions of room temperature, 500 MHz and 16 times of accumulation.Tetramethylsilane was used as an internal standard. In ¹⁹F-NMRmeasurement, CFCl₃ was used as an internal standard, and measurement wascarried out under conditions of 24 times of accumulation. In explainingnuclear magnetic resonance spectra obtained, s, d, t, q, quin, sex and mstand for a singlet, a doublet, a triplet, a quartet, a quintet, asextet and a multiplet, and br being broad, respectively.

Gas chromatographic analysis: For measurement, GC-2010 Gas Chromatographmade by Shimadzu Corporation was used. As a column, a capillary columnDB-1 (length 60 m, bore 0.25 mm, film thickness 0.25 μm) made by AgilentTechnologies, Inc. was used. As a carrier gas, helium (1 mL/minute) wasused. A temperature of a sample vaporizing chamber and a temperature ofa detector (FID) were set to 300° C. and 300° C., respectively. A samplewas dissolved in acetone and prepared to be a 1 weight % solution, andthen 1 microliter of the solution obtained was injected into the samplevaporizing chamber. As a recorder, GC Solution System made by ShimadzuCorporation or the like was used.

Gas chromatography mass analysis: For measurement, QP-2010 Ultra GasChromatograph Mass Spectrometer made by Shimadzu Corporation was used.As a column, a capillary column DB-1 (length 60 m, bore 0.25 mm, filmthickness 0.25 μm) made by Agilent Technologies, Inc. was used. As acarrier gas, helium (1 mL/minute) was used. A temperature of a samplevaporizing chamber, a temperature of an ion source, ionizing voltage andemission current were set to 300° C., 200° C., 70 eV and 150 uA,respectively. A sample was dissolved in acetone and prepared to be a 1weight % solution, and then 1 microliter of the solution obtained wasinjected into the sample vaporizing chamber. As a recorder, GCMSsolution system made by Shimadzu Corporation was used.

HPLC Analysis: For measurement, Prominence (LC-20AD; SPD-20A) made byShimadzu Corporation was used. As a column, YMC-Pack ODS-A (length 150mm, bore 4.6 mm, particle diameter 5 μm) made by YMC Co., Ltd. was used.As an eluate, acetonitrile and water were appropriately mixed and used.As a detector, a UV detector, an RI detector, a CORONA detector or thelike was appropriately used. When the UV detector was used, a detectionwavelength was set to 254 nanometers. A sample was dissolved inacetonitrile and prepared to be a 0.1 weight % solution, and then 1microliter of the solution was introduced into a sample chamber. As arecorder, C-R7Aplus made by Shimadzu Corporation was used.

Ultraviolet-Visible spectrophotometry: For measurement, PharmaSpecUV-1700 made by Shimadzu Corporation was used. A detection wavelengthwas adjusted in the range of 190 nanometers to 700 nanometers. A samplewas dissolved in acetonitrile and prepared to be a 0.01 mmol/L solution,and measurement was carried out by putting the solution in a quartz cell(optical path length: 1 cm).

Sample for measurement: Upon measuring phase structure and a transitiontemperature (a clearing point, a melting point, a polymerizationstarting temperature or the like), the compound itself was used as asample. Upon measuring physical properties such as maximum temperatureof a nematic phase, viscosity, optical anisotropy and dielectricanisotropy, a mixture of the compound and a base liquid crystal was usedas a sample.

When the sample prepared by mixing the compound with the base liquidcrystal was used, measurement was carried out as described below. Thesample was prepared by mixing 15% by weight of the compound and 85% byweight of the base liquid crystal. From a measured value of the sample,an extrapolated value was calculated according to the followingequation, and the calculated value was described: [extrapolatedvalue]=(100×[measured value of a sample]−[% by weight of a base liquidcrystal]×[measured value of the base liquid crystal])/[% by weight of acompound].

When crystals (or a smectic phase) precipitated at 25° C. at the ratio,a ratio of the compound to the base liquid crystal was changed in theorder of (10% by weight:90% by weight), (5% by weight:95% by weight),and (1% by weight:99% by weight), and the physical properties of thesample were measured at a ratio at which no crystal (or no smecticphase) precipitated at 25° C. In addition, unless otherwise noted, theratio of the compound to the base liquid crystal was (15% by weight:85%by weight)

When the dielectric anisotropy of the compound was zero or positive,base liquid crystal (A) described below was used. A proportion of eachcomponent was expressed in terms of weight percent (% by weight).

When the dielectric anisotropy of the compound was zero or negative,base liquid crystal (B) described below was used. A proportion of eachcomponent was expressed in terms of weight percent (% by weight).

Measuring method: Physical properties were measured according to methodsdescribed below. Most of the methods are described in the Standard ofJapan Electronics and Information Technology Industries Association(JEITA) discussed and established in JEITA (JEITA ED-2521B). Amodification of the methods were also used. No thin film transistor(TFT) was attached to a TN device used for measurement.

(1) Phase structure: A sample was placed on a hot plate in a meltingpoint apparatus (FP-52 Hot Stage made by Mettler-Toledo InternationalInc.) equipped with a polarizing microscope. A state of phase and achange thereof were observed with the polarizing microscope while thesample was heated at a rate of 3° C. per minute, and a kind of the phasewas specified.

(2) Transition temperature (° C.): For measurement, a differentialscanning calorimeter, Diamond DSC System, made by PerkinElmer, Inc., ora high sensitivity differential scanning calorimeter, X-DSC7000, made bySII NanoTechnology Inc. was used. A sample was heated and then cooled ata rate of 3° C. per minute, and a starting point of an endothermic peakor an exothermic peak caused by a phase change of the sample wasdetermined by extrapolation, and thus a transition temperature wasdetermined. A melting point and a polymerization starting temperature ofa compound were also measured using the apparatus. Temperature at whicha compound undergoes transition from a solid to a liquid crystal phasesuch as the smectic phase and the nematic phase may be occasionallyabbreviated as “minimum temperature of the liquid crystal phase.”Temperature at which the compound undergoes transition from the liquidcrystal phase to liquid may be occasionally abbreviated as “clearingpoint.”

A crystal was expressed as C. When the crystals were distinguishableinto two kinds, each of the crystals was expressed as C₁ or C₂. Thesmectic phase or the nematic phase was expressed as S or N. When a phasewas distinguishable such as smectic A phase, smectic B phase, smectic Cphase and smectic F, the phase was expressed as S_(A), S_(B), S_(C) andS_(F), respectively. A liquid (isotropic) was expressed as I. Atransition temperature was expressed as “C 50.0 N 100.0 I,” for example.The expression indicates that a transition temperature from the crystalsto the nematic phase is 50.0° C., and a transition temperature from thenematic phase to the liquid is 100.0° C.

(3) Compatibility of compound: Samples in which the base liquid crystaland the compound were mixed for proportions of the compounds to be 20%by weight, 15% by weight, 10% by weight, 5% by weight, 3% by weight or1% by weight were prepared. The samples were put in a glass vials, andkept in freezers at −10° C. or −20° C. for a predetermined period oftime. Whether a nematic phase of the samples was maintained or crystals(or a smectic phase) precipitated was observed. Conditions on which thenematic phase was maintained were used as a measure of thecompatibility. Proportions of the compounds and each temperature in thefreezers may be occasionally changed when necessary.

(4) Maximum temperature of nematic phase (T_(NI) or NI; ° C.): A samplewas placed on a hot plate in a melting point apparatus equipped with apolarizing microscope, and heated at a rate of 1° C. per minute.Temperature when part of the sample began to change from a nematic phaseto an isotropic liquid was measured. When the sample was a mixture ofcompound (1) and the base liquid crystal, the maximum temperature wasexpressed in terms of a symbol T_(NI). When the sample was a mixture ofcompound (1) and a compound selected from compounds (2) to (15), themaximum temperature was expressed in terms of a symbol NI. A maximumtemperature of the nematic phase may be occasionally abbreviated as“maximum temperature.”

(5) Minimum temperature of nematic phase (T_(C); ° C.): Samples eachhaving a nematic phase were put in glass vials and kept in freezers attemperatures of 0° C., −10° C., −20° C., −30° C. and −40° C. for 10days, and then liquid crystal phases were observed. For example, whenthe sample was maintained in the nematic phase at −20° C. and changed tocrystals or a smectic phase at −30° C., T_(C) was expressed asT_(C)<−20° C. A minimum temperature of the nematic phase may beoccasionally abbreviated as “minimum temperature.”

(6) Viscosity (bulk viscosity; η; measured at 20° C.; mPa·s): Formeasurement, a cone-plate (E type) rotational viscometer made by TokyoKeiki Inc. was used.

(7) Optical anisotropy (refractive index anisotropy; measured at 25° C.;Δn): Measurement was carried out by an Abbe refractometer with apolarizing plate mounted on an ocular, using light at a wavelength of589 nanometers. A surface of a main prism was rubbed in one direction,and then a sample was added dropwise onto the main prism. A refractiveindex (n∥) was measured when a direction of polarized light was parallelto a direction of rubbing. A refractive index (n⊥) was measured when thedirection of polarized light was perpendicular to the direction ofrubbing. A value of optical anisotropy (Δn) was calculated from anequation: Δn=n∥−n⊥.

(8) Specific resistance (ρ; measured at 25° C.; Ωcm): Into a vesselequipped with electrodes, 1.0 milliliter of sample was injected. Adirect current voltage (10 V) was applied to the vessel, and a directcurrent after 10 seconds was measured. Specific resistance wascalculated from the following equation:

(specific resistance)={(voltage)×(electric capacity of avessel)}/{(direct current)×(dielectric constant of vacuum)}.

(9) Voltage holding ratio (VHR-1; measured at 25° C.; %): A TN deviceused for measurement had a polyimide alignment film, and a distance(cell gap) between two glass substrates was 5 micrometers. A sample wasput in the device, and then the device was sealed with anultraviolet-curable adhesive. The device was charged by applying a pulsevoltage (60 microseconds at 5 V). A decaying voltage was measured for16.7 milliseconds with a high-speed voltmeter, and area A between avoltage curve and a horizontal axis in a unit cycle was determined. AreaB is an area without decay. A voltage holding ratio is expressed interms of a percentage of area A to area B.

(10) Voltage holding ratio (VHR-2; measured at 80° C.; %): A voltageholding ratio was measured according to the method described aboveexcept that the voltage holding ratio was measured at 80° C. in place of25° C. The results obtained were expressed in terms of a symbol VHR-2.

(11) Flicker rate (measured at 25° C.; %): For measurement, 3298FMultimedia Display Tester made by Yokogawa Electric Corporation wasused. A light source was LED. A sample was put in a normally black modeFFS device in which a distance (cell gap) between two glass substrateswas 3.5 micrometers, and a rubbing direction was anti-parallel. Thedevice was sealed with an ultraviolet-curable adhesive. Voltage wasapplied to the device, and a voltage having a maximum amount of lighttransmitted through the device was measured. A sensor part was broughtclose to the device while the voltage was applied, and a flicker ratedisplayed thereon was read.

The measuring method of the physical properties may be different betweena sample having positive dielectric anisotropy and a sample havingnegative dielectric anisotropy. When the dielectric anisotropy waspositive, the measuring method was described in measurement (12a) tomeasurement (16a). When the dielectric anisotropy was negative, themeasuring method was described in measurement (12b) to measurement(16b).

(12a) Viscosity (rotational viscosity; γ1; measured at 25° C.; mPa·s;for a sample having positive dielectric anisotropy): Measurement wascarried out according to a method described in M. Imai et al., MolecularCrystals and Liquid Crystals, Vol. 259, p. 37 (1995). A sample was putin a TN device in which a twist angle was 0 degrees and a distance (cellgap) between two glass substrates was 5 micrometers. Voltage was appliedstepwise to the device from 16 V to 19.5 V at an increment of 0.5 V.After a period of 0.2 second with no voltage application, voltage wasrepeatedly applied under conditions of only one rectangular wave(rectangular pulse; 0.2 second) and no voltage application (2 seconds).A peak current and a peak time of transient current generated by theapplied voltage were measured. A value of rotational viscosity wasobtained from the measured values and equation (8) on page 40 of thepaper presented by M. Imai et al. A value of dielectric anisotropyrequired for the calculation was determined using the device by whichthe rotational viscosity was measured and by a method described below.

(12b) Viscosity (rotational viscosity; γ1; measured at 25° C.; mPa·s;for a sample having negative dielectric anisotropy): Measurement wascarried out according to the method described in M. Imai et al.,Molecular Crystals and Liquid Crystals, Vol. 259, p. 37 (1995). A samplewas put in a VA device in which a distance (cell gap) between two glasssubstrates was 20 micrometers. Voltage was applied stepwise to thedevice from 39 V to 50 V at an increment of 1 V. After a period of 0.2second with no voltage application, voltage was repeatedly applied underconditions of only one rectangular wave (rectangular pulse; 0.2 second)and no voltage application (2 seconds). A peak current and a peak timeof transient current generated by the applied voltage were measured. Avalue of rotational viscosity was obtained from the measured values andequation (8) on page 40 of the paper presented by M. Imai et al.Dielectric anisotropy required for the calculation was measured in asection of dielectric anisotropy described below.

(13a) Dielectric anisotropy (Δε; measured at 25° C.; for a sample havingpositive dielectric anisotropy): A sample was put in a TN device inwhich a distance (cell gap) between two glass substrates was 9micrometers and a twist angle was 80 degrees. Sine waves (10 V, 1 kHz)were applied to the device, and after 2 seconds, a dielectric constant(ε∥) of liquid crystal molecules in a major axis direction was measured.Sine waves (0.5 V, 1 kHz) were applied to the device, and after 2seconds, a dielectric constant (ε⊥) of liquid crystal molecules in aminor axis direction was measured. A value of dielectric anisotropy wascalculated from an equation: Δε=ε∥−ε⊥.

(13b) Dielectric anisotropy (Δε; measured at 25° C.; for a sample havingnegative dielectric anisotropy): A value of dielectric anisotropy wascalculated from the equation: Δε=ε∥−ε⊥. A dielectric constant (εν andε⊥) was measured as described below.

(1) Measurement of dielectric constant (ε∥): An ethanol (20 mL) solutionof octadecyltriethoxysilane (0.16 mL) was applied to a well-cleanedglass substrate. After rotating the glass substrate with a spinner, theglass substrate was heated at 150° C. for 1 hour. A sample was put in aVA device in which a distance (cell gap) between two glass substrateswas 4 micrometers, and the device was sealed with an ultraviolet-curableadhesive. Sine waves (0.5 V, 1 kHz) were applied to the device, andafter 2 seconds, a dielectric constant (ε∥) of liquid crystal moleculesin a major axis direction was measured.

(2) Measurement of dielectric constant (ε⊥): A polyimide solution wasapplied to a well-cleaned glass substrate. After calcining the glasssubstrate, rubbing treatment was applied to the alignment film obtained.A sample was put in a TN device in which a distance (cell gap) betweentwo glass substrates was 9 micrometers and a twist angle was 80 degrees.Sine waves (0.5 V, 1 kHz) were applied to the device, and after 2seconds, a dielectric constant (ε⊥) of liquid crystal molecules in aminor axis direction was measured.

(14a) Elastic constant (K; measured at 25° C.; pN; for a sample havingpositive dielectric anisotropy): For measurement, HP4284A LCR Meter madeby Yokogawa-Hewlett-Packard Co. was used. A sample was put in ahorizontal alignment device in which a distance (cell gap) between twoglass substrates was 20 micrometers. An electric charge from 0 V to 20 Vwas applied to the device, and electrostatic capacity (C) and appliedvoltage (V) were measured. The measured values were fitted to equation(2.98) and equation (2.101) on page 75 of “Liquid Crystal DeviceHandbook (Ekisho Debaisu Handobukku in Japanese; Nikkan Kogyo Shimbun,Ltd.),” and values of K₁₁ and K₃₃ were obtained from equation (2.99).Next, K₂₂ was calculated using the previously determined values of K₁₁and K₃₃ in equation (3.18) on page 171. Elastic constant K was expressedin terms of a mean value of the thus determined K₁₁, K₂₂ and K₃₃.

(14b) Elastic constant (K₁₁ and K₃₃; measured at 25° C.; pN; for asample having negative dielectric anisotropy): For measurement, ElasticConstant Measurement System Model EC-1 made by TOYO Corporation wasused. A sample was put in a vertical alignment device in which adistance (cell gap) between two glass substrates was 20 micrometers. Anelectric charge from 20 V to 0 V was applied to the device, andelectrostatic capacity (C) and applied voltage (V) were measured. Themeasured values were fitted to equation (2.98) and equation (2.101) onpage 75 of “Liquid Crystal Device Handbook (Ekisho Debaisu Handobukku inJapanese; Nikkan Kogyo Shimbun, Ltd.),” and values of elastic constantswere obtained from equation (2.100).

(15a) Threshold voltage (Vth; measured at 25° C.; V; for a sample havingpositive dielectric anisotropy): For measurement, an LCD-5100 luminancemeter made by Otsuka Electronics Co., Ltd. was used. A light source wasa halogen lamp. A sample was put in a normally white mode TN device inwhich a distance (cell gap) between two glass substrates was 0.45/Δn(μm) and a twist angle was 80 degrees. A voltage (32 Hz, rectangularwaves) to be applied to the device was stepwise increased from 0 V to 10V at an increment of 0.02 V. On the occasion, the device was irradiatedwith light from a direction perpendicular to the device, and an amountof light transmitted through the device was measured. Avoltage-transmittance curve was prepared, in which the maximum amount oflight corresponds to 100% transmittance and the minimum amount of lightcorresponds to 0% transmittance. A threshold voltage is expressed interms of voltage at 90% transmittance.

(15b) Threshold voltage (Vth; measured at 25° C.; V; for a sample havingnegative dielectric anisotropy): For measurement, an LCD-5100 luminancemeter made by Otsuka Electronics Co., Ltd. was used. A light source wasa halogen lamp. A sample was put in a normally black mode VA device inwhich a distance (cell gap) between two glass substrates was 4micrometers and a rubbing direction was anti-parallel, and the devicewas sealed with an ultraviolet-curable adhesive. A voltage (60 Hz,rectangular waves) to be applied to the device was stepwise increasedfrom 0 V to 20 V at an increment of 0.02 V. On the occasion, the devicewas irradiated with light from a direction perpendicular to the device,and an amount of light transmitted through the device was measured. Avoltage-transmittance curve was prepared, in which the maximum amount oflight corresponds to 100% transmittance and the minimum amount of lightcorresponds to 0% transmittance. A threshold voltage is expressed interms of voltage at 10% transmittance.

(16a) Response time (τ; measured at 25° C.; ms; for a sample havingpositive dielectric anisotropy): For measurement, an LCD-5100 luminancemeter made by Otsuka Electronics Co., Ltd. was used. A light source wasa halogen lamp. A low-pass filter was set to 5 kHz. A sample was put ina normally white mode TN device in which a distance (cell gap) betweentwo glass substrates was 5.0 micrometers and a twist angle was 80degrees. A voltage (rectangular waves; 60 Hz, 5 V, 0.5 second) wasapplied to the device. On the occasion, the device was irradiated withlight from a direction perpendicular to the device, and an amount oflight transmitted through the device was measured. The maximum amount oflight corresponds to 100% transmittance, and the minimum amount of lightcorresponds to 0% transmittance. Arise time (τr; millisecond) wasexpressed in terms of time required for a change from 90% transmittanceto 10% transmittance. A fall time (τf; millisecond) was expressed interms of time required for a change from 10% transmittance to 90%transmittance. A response time was expressed by a sum of the rise timeand the fall time thus determined.

(16b) Response time (τ; measured at 25° C.; ms; for a sample havingnegative dielectric anisotropy): For measurement, an LCD-5100 luminancemeter made by Otsuka Electronics Co., Ltd. was used. A light source wasa halogen lamp. A low-pass filter was set to 5 kHz. A sample was put ina normally black mode PVA device in which a distance (cell gap) betweentwo glass substrates was 3.2 micrometers, and a rubbing direction wasanti-parallel. The device was sealed with an ultraviolet-curableadhesive. The device was applied with a voltage of a little exceeding athreshold voltage for 1 minute, and then was irradiated with ultravioletlight of 23.5 mW/cm² for 8 minutes, while applying a voltage of 5.6 V. Avoltage (rectangular waves; 60 Hz, 10 V, 0.5 second) was applied to thedevice. On the occasion, the device was irradiated with light from adirection perpendicular to the device, and an amount of lighttransmitted through the device was measured. The maximum amount of lightcorresponds to 100% transmittance, and the minimum amount of lightcorresponds to 0% transmittance. A response time was expressed in termsof time required for a change from 90% transmittance to 10%transmittance (fall time; millisecond).

Synthesis Example 1 Synthesis of Compound (1-1-7)

First Step: Synthesis of Compound (T-2)

Under a nitrogen atmosphere, compound (T-1) (35.0 g), potassiumcarbonate (27.7 g), DMF (350 mL) and bromopentane (30.4 g) were put in areaction vessel, and the resulting mixture was stirred at 90° C. for 2hours. The resulting reaction mixture was poured into ice water, and anaqueous layer was subjected to extraction with toluene. Combined organiclayers were washed with water, and dried over anhydrous magnesiumsulfate. The solution was concentrated under reduced pressure, and theresidue was purified by silica gel chromatography (heptane) to obtaincompound (T-2) (45.1 g, yield: 96%).

Second Step: Synthesis of Compound (T-3)

Under a nitrogen atmosphere, a diethyl ether solution (100 mL) ofcompound (T-2) (20.0 g) was cooled down to −40° C. Then, n-butyllithium(1.64 M; hexane solution; 48.4 mL) was slowly added, and stirred at −40°C. for 1 hour. Thereto, a diethyl ether solution (50 mL) of trimethylborate (9.6 mL) was added dropwise, and the resulting solution wasreturned to room temperature while stirring. The resulting reactionmixture was cooled down to −5° C. Thereto, a diethyl ether solution (50mL) of acetic acid (8.2 mL) was added dropwise, and the resultingmixture was stirred for 30 minutes. Next, hydrogen peroxide (30%solution; 4.9 g) was added dropwise thereto. The resulting reactionmixture was poured into water, and an ordinary post-treatment wasapplied thereto, and the resulting solution was purified by silica gelchromatography (heptane:ethyl acetate=4:1 in a volume ratio) to obtaincompound (T-3) (13.0 g, yield: 83%).

Third Step: Synthesis of Compound (T-5)

Under a nitrogen atmosphere, a THF (240 mL) solution of compound (T-4)(24.0 g) was cooled down to −70° C. Then, lithium diisopropylamide (LDA;1.01 M; THF solution; 204.1 mL) was slowly added thereto, and theresulting solution was stirred for 2 hours while maintaining −70° C.Thereto, methanol (100 mL) was added, and the resulting solution waspoured into water. An ordinary post-treatment was applied thereto, andthe resulting solution was purified by silica gel chromatography(heptane) to obtain compound (T-5) (19.8 g, yield: 78%).

Fourth Step: Synthesis of Compound (T-6)

Under a nitrogen atmosphere, a diethyl ether solution (50 mL) ofcompound (T-5) (5.0 g) was cooled down to −40° C. Then, n-butyllithium(1.64 M; hexane solution; 14.4 mL) was slowly added, and the resultingsolution was stirred at −40° C. for 1 hour. Thereto, a diethyl ethersolution (50 mL) of iodine (6.5 g) was added dropwise, and the resultingsolution was returned to room temperature while stirring. The resultingreaction mixture was poured into water, and an ordinary post-treatmentwas applied thereto, and the resulting solution was purified by silicagel chromatography (heptane) to obtain compound (T-6) (4.35 g, yield:61%).

Fifth Step: Synthesis of Compound (T-7)

Under a nitrogen atmosphere, compound (T-3) (6.1 g), copper(I) chloride(0.7 g), cesium carbonate (9.2 g), 2,2,6,6-tetramethyl-3,5-heptanedione(0.3 g) and N-methyl-2-pyrrolidone (80 mL) were added to compound (T-6)(4.0 g), and the resulting solution was stirred and heated at 120° C.for 6 hours. The resulting reaction mixture was poured into 1 Nhydrochloric acid, and an ordinary post-treatment was applied thereto,and the resulting solution was purified by silica gel chromatography(heptane) to obtain compound (T-7) (2.1 g, yield: 34%).

Sixth Step: Synthesis of Compound (1-1-7)

Under a synthetic nitrogen atmosphere, a THF (20 mL) solution ofcompound (T-7) (2.1 g) was cooled down to −70° C. Then, n-butyllithium(1.64 M; hexane solution; 8.0 mL) was slowly added, and the resultingsolution was stirred at −70° C. for 3 hours. Thereto, iron(III) chloridedried under reduced pressure for 3 hours at 100° C. was added, and theresulting solution was returned to room temperature while stirring. Theresulting reaction mixture was poured into 1 N hydrochloric acid, and anordinary post-treatment was applied thereto, and the resulting solutionwas purified by silica gel chromatography (heptane) andrecrystallization to obtain compound (1-1-7) (0.43 g, yield: 20%).

¹H-NMR (CDCl₃; δ ppm): 7.11-7.09 (m, 1H), 6.93-6.11 (m, 1H), 4.10 (t,J=6.5 Hz, 2H), 2.80-2.77 (m, 2H), 1.89-1.88 (m, 2H), 1.72-1.70 (m, 2H),1.55-1.38 (m, 4H), 1.00-0.95 (m, 6H).

Phase transition temperature: C 81.8 I.

Maximum temperature (NI)=−15.7° C.; optical anisotropy (Δn)=0.140;dielectric anisotropy (Δε)=−7.2; viscosity (η)=98.5 mPa·s.

Synthesis Example 2 Synthesis of Compound (1-2-22)

First Step: Synthesis of Compound (T-9)

Compound (T-9) (9.76 g, yield: 63%) was obtained by using compound (T-8)(15.0 g) as a raw material in a manner similar to the technique in thethird step in Synthesis Example 1.

Second Step: Synthesis of Compound (T-10)

Compound (T-10) (8.87 g, yield: 66%) was obtained in a manner similar tothe technique in the fourth step in Synthesis Example 1.

Third Step: Synthesis of Compound (T-12)

Compound (T-12) (3.8 g, yield: 28%) was obtained by using compound(T-10) (8.87 g) and compound (T-11) (8.0 g) as a raw material in amanner similar to the technique in the fifth step in Synthesis Example1.

Fourth Step: Synthesis of Compound (1-2-22)

Compound (1-2-22) (1.05 g, yield: 34%) was obtained by using compound(T-12) (3.1 g) as a raw material in a manner similar to the technique inthe sixth step in Synthesis Example 1.

¹H-NMR (CDCl₃; δ ppm): 7.54-7.51 (m, 2H), 7.36-7.29 (m, 3H), 6.94-6.97(m, 1H), 4.20 (q, J=7.0 Hz, 2H), 2.67 (t, J=7.9 Hz, 2H), 1.70-1.63 (m,2H), 1.55-1.52 (m, 4H), 1.38-1.35 (m, 3H), 0.93-0.90 (m, 3H).

Phase transition temperature: C 123.5 I.

Maximum temperature (NI)=114.3° C.; optical anisotropy (Δn)=0.254;dielectric anisotropy (Δε)=−10.1; viscosity (η)=82.7 mPa·s.

In addition, a sample having a ratio of the compound to a base liquidcrystal (3% by weight:97% by weight) was used for measurement of themaximum temperature, the optical anisotropy, the dielectric anisotropyand the viscosity.

Synthesis Example 3 Synthesis of Compound (1-2-43)

First Step: Synthesis of Compound (T-15)

Compound (T-15) (22.5 g, yield: 71%) was obtained by using compound(T-14) (22.0 g) prepared according to a publicly known method in placeof bromopentane in a manner similar to the technique in the first stepin Synthesis Example 1.

Second Step: Synthesis of Compound (T-16)

Compound (T-16) (19.8 g, yield: 71%) was obtained in a manner similar tothe technique in the fourth step in Synthesis Example 1.

Third Step: Synthesis of Compound (T-17)

Compound (T-17) (11.2 g, yield: 80%) was obtained by using compound(T-5) (19.0 g) as a raw material in a manner similar to the technique inthe second step in Synthesis Example 1.

Fourth Step: Synthesis of Compound (T-18)

Compound (T-18) (8.3 g, yield: 35%) was obtained by using compound(T-16) (12.1 g) and compound (T-17) (9.9 g) as a raw material in amanner similar to the technique in the fifth step in Synthesis Example1.

Fifth Step: Synthesis of Compound (1-2-43)

Compound (1-2-43) (2.86 g, yield: 35%) was obtained by using compound(T-18) (8.3 g) as a raw material in a manner similar to the technique inthe sixth step in Synthesis Example 1.

¹H-NMR (CDCl₃; δ ppm): 7.10 (d, J=4.3 Hz, 1H), 6.90 (dd, J=5.6 Hz, 1.0Hz, 1H), 3.89 (d, J=6.4 Hz, 2H), 2.77 (t, J=7.5 Hz, 2H), 1.95-1.82 (m,5H), 1.73-1.69 (m, 2H), 1.33-1.18 (m, 9H), 1.14-1.06 (m, 2H), 1.01-0.89(m, 8H)

Phase transition temperature: C 84.2 S_(A) 95.9 N 101.2 I.

Maximum temperature (NI)=89.0° C.; optical anisotropy (Δn)=0.167;dielectric anisotropy (Δε)=−8.24; viscosity (η)=117.8 mPa·s.

Synthesis Example 4 Synthesis of Compound (1-2-49)

First Step: Synthesis of Compound (T-20)

A dichloromethane (100 mL) solution of compound (T-19) (35.0 g) preparedaccording to a publicly known method and carbon tetrabromide (93.5 g)was cooled down to 0° C. Thereto, a dichloromethane (75 mL) solution oftriphenyl phosphine (98.6 g) was added dropwise, and the resultingsolution was returned to room temperature while stirring. Δn ordinarypost-treatment was applied thereto, and the resulting solution waspurified by silica gel chromatography (toluene) to obtain compound(T-20) (38.6 g, 145.9 mmol; 78%).

Second Step: Synthesis of Compound (T-21)

Compound (T-21) (22.0 g, yield: 38%) was obtained by using compound(T-20) (38.6 g) in place of iodoethane in a manner similar to thetechnique in the first step in Synthesis Example 1.

Third Step: Synthesis of Compound (T-22)

Compound (T-22) (5.2 g, yield: 66%) was obtained by using compound(T-21) (5.5 g) and compound (T-17) (5.0 g) as a raw material in a mannersimilar to the technique in the fifth step in Synthesis Example 1.

Fourth Step: Synthesis of Compound (1-2-49)

Compound (1-2-49) (2.52 g, yield: 55%) was obtained by using compound(T-22) (4.2 g) as a raw material in a manner similar to the technique inthe sixth step in Synthesis Example 1.

¹H-NMR (CDCl₃; δ ppm): 7.10 (d, J=4.3 Hz, 1H), 6.90 (dd, J=5.6 Hz, 1.0Hz, 1H), 4.22-4.18 (m, 1H), 3.95-3.87 (m, 2H), 3.33-3.23 (m, 52H),2.23-2.19 (m, 1H), 2.01-1.98 (m, 1H), 1.74-1.67 (m, 3H), 1.56-1.51 (m,2H), 1.45-1.26 (m, 10H), 1.01-0.98 (m, 3H), 0.99-0.86 (m, 3H)

Phase transition temperature: C 89.0 S_(A) 99.6 I.

Maximum temperature (NI)=77.6° C.; optical anisotropy (Δn)=0.160;dielectric anisotropy (Δε)=−10.52; viscosity (η)=151.7 mPa·s.

Synthesis Example 5 Synthesis of Compound (1-2-29)

First Step: Synthesis of Compound (T-25)

Under a nitrogen atmosphere, Solmix (120 mL) and water (24 mL) wereadded to a toluene (120 mL) solution of compound (T-23) (12.0 g),compound (T-24) (7.8 g), potassium carbonate (11.4 g),tetrabutylammonium bromide (TBAB; 3.3 g) andtetrakis(triphenylphosphine)palladium (0) (2.4 g), and the resultingsolution was stirred and heated for 2 hours. The resulting reactionmixture was poured into water, and an ordinary post-treatment wasapplied thereto, and the resulting solution was purified by silica gelchromatography (heptane) to obtain compound (T-25) (6.61 g, yield: 55%).

Second Step: Synthesis of Compound (T-26)

Under a nitrogen atmosphere, a THF solution (100 mL) of compound (T-25)(6.61 g) was cooled down to −70° C. Then, sec-butyllithium (1.05 M;hexane solution; 27.1 mL) was slowly added, and the resulting solutionwas stirred at −70° C. for 3 hours. Thereto, a cyclohexane solution (10mL) of bromine (1.47 mL) was added dropwise, and the resulting solutionwas returned to room temperature while stirring. The resulting reactionmixture was poured into water, and an ordinary post-treatment wasapplied thereto, and the resulting solution was purified by silica gelchromatography (heptane) to obtain compound (T-26) (6.15 g, yield: 71%).

Third Step: Synthesis of Compound (T-27)

Compound (T-27) (5.54 g, yield: 90%) was obtained by using compound(T-26) (6.15 g) as a raw material in a manner similar to the techniquein the third step in Synthesis Example 1.

Fourth Step: Synthesis of Compound (T-28)

Compound (T-28) (2.0 g, yield: 60%) was obtained by using compound(T-27) (3.89 g) as a raw material in a manner similar to the techniquein the fifth step in Synthesis Example 1.

Fifth Step: Synthesis of Compound (1-2-29)

Compound (1-2-29) (0.27 g, yield: 15%) was obtained by using compound(T-12) (1.8 g) as a raw material in a manner similar to the technique inthe sixth step in Synthesis Example 1.

¹H-NMR (CDCl₃; δ ppm): 7.37-7.31 (m, 2H), 7.09-7.02 (m, 2H), 6.97-6.94(m, 1H), 4.21 (q, J=7.0 Hz, 2H), 3.69-3.61 (m, 2H), 1.71-1.64 (m, 2H),1.56-1.52 (m, 3H), 1.39-1.35 (m, 4H), 0.94-0.90 (m, 3H)

Phase transition temperature: C 94.5 I.

Maximum temperature (NI)=70.3° C.; optical anisotropy (Δn)=0.227;dielectric anisotropy (Δε)=−9.2.

Comparative Example 1

As a comparative compound, compound (S-1) described below disclosed inJP H10-236992 A was selected. The compound was prepared according to apublicly known method.

¹H-NMR (CDCl₃; δ ppm): 7.03 (d, J=5.6 Hz, 1H), 6.89 (d, J=6.2 Hz, 1H),3.87 (d, J=6.4 Hz, 2H), 3.84 (s, 2H), 2.67 (t, J=7.3 Hz, 2H), 1.97-1.90(m, 2H), 1.88-1.77 (m, 3H), 1.72-1.63 (m, 2H), 1.36-1.16 (m, 9H),1.15-1.02 (m, 2H), 1.01-0.86 (m, 8H).

Physical properties of compound (S-1) were as described below. Inaddition, a sample having a ratio of the compound to the base liquidcrystal (3% by weight:97% by weight) was used for measurement of themaximum temperature, the optical anisotropy, the dielectric anisotropyand the viscosity.

Transition temperature: C 157 I.

Maximum temperature (T_(NI))=97.9° C.; optical anisotropy (Δn)=0.147;dielectric anisotropy (Δε)=−13.1; viscosity (η)=98.9 mPa·s.

The results obtained by measuring the compatibility with regard tocompound (1-2-43), compound (1-2-49) and compound (S-1) are summarizedin Table 2. Samples for measurement were prepared according to the“extrapolation method” described above. Then, 15% by weight of compound(1-2-43) and compound (1-2-49) each was mixed with 85% by weight ofliquid crystal (B), and dissolved therein by heating the mixture. Themixture was returned to room temperature, but no crystals precipitated.In contrast, when compound (S-1) was dissolved in liquid crystal (B) inan identical proportion and the resulting solution was returned to roomtemperature, crystals precipitated. The proportion of the compound (S-1)was changed to 10% by weight or 5% by weight, but crystals precipitated.When the proportion was 3% by weight, no crystals precipitated. Theresults show that compound (1-2-43) and compound (1-2-49) were excellentin the compatibility because an oxygen atom of a fluorodibenzofuran ringhas an effect of degrading crystallinity. When the refractive indexanisotropy (Δn) of the samples was measured, compound (1-2-43) andcompound (1-2-49) had a larger value. The results show that compound(1-2-43) and compound (1-2-49) having the fluorodibenzofuran ring aresuperior to comparative compound (S-1).

TABLE 2 Compatibility and refractive index anisotropy of compoundCompatibility Refractive (ratio of index Compound Structural formulacompound) anisotropy (Δn) Compound (1-2-43)

15% by weight: 85% by weight  0.167 Compound (1-2-49)

15% by weight: 85% by weight  0.160 Compound (S-1)

 3% by weight: 97% by weight  0.147

Comparative Example 2

As a comparative compound, compound (S-2) described below disclosed inJP 2015-174864 A was selected. The compound was prepared according to apublicly known method.

¹H-NMR (CDCl₃; δ ppm): 7.52-7.51 (m, 2H), 7.14-7.11 (m, 1H), 7.02-6.98(m, 1H), 4.14 (t, J=6.7 Hz, 2H), 2.78 (t, J=7.5 Hz, 2H), 1.90-1.84 (m,2H), 1.73-1.69 (m, 2H), 1.52-1.39 (m, 4H), 1.00-0.94 (m, 6H).

Physical properties of compound (S-2) were as described below.

Transition temperature: C 54.8 I.

Maximum temperature (T_(NI))=−12.4° C.; optical anisotropy (Δn)=0.16;dielectric anisotropy (Δε)=−6.9; viscosity (η)=55.8 mPa·s.

The results obtained by measuring the dielectric anisotropy of compound(1-1-7) and compound (S-2) are summarized in Table 3. Samples formeasurement were prepared according to the “extrapolation method”described above. Compound (1-1-7) had negatively larger value. Theresults show that compound (1-1-7) having a fluorine group in a positionon a side reverse to an oxygen atom of a fluorodibenzofuran ring issuperb in comparison with comparative compound (S-2)

TABLE 3 Dielectric anisotropy of compound Dielectric anisotropy CompoundStructural formula (Δε) Compound (1-1-7)

−7.2 Compound (S-2)

−6.9

Compounds shown below can be prepared with reference to the methoddescribed in Synthesis Examples and the section “2. Synthesis ofcompound (1).”

No. 1-1-1 

1-1-2 

1-1-3 

1-1-4 

1-1-5 

1-1-6 

1-1-7 

1-1-8 

1-1-9 

1-1-10

1-1-11

1-1-12

1-1-13

1-1-14

1-1-15

1-1-16

1-1-17

1-1-18

1-1-19

1-1-20

1-2-1 

1-2-2 

1-2-3 

1-2-4 

1-2-5 

1-2-6 

1-2-7 

1-2-8 

1-2-9 

1-2-10

1-2-11

1-2-12

1-2-13

1-2-14

1-2-15

1-2-16

1-2-17

1-2-18

1-2-19

1-2-20

1-2-21

1-2-22

1-2-23

1-2-24

1-2-25

1-2-26

1-2-27

1-2-28

1-2-29

1-2-30

1-2-31

1-2-32

1-2-33

1-2-34

1-2-35

1-2-36

1-2-37

1-2-38

1-2-39

1-2-40

1-2-41

1-2-42

1-2-43

1-2-44

1-2-45

1-2-46

1-2-47

1-2-48

1-2-49

1-2-50

1-2-51

1-2-52

1-2-53

1-2-54

1-2-55

1-2-56

1-2-57

1-2-58

1-2-59

1-2-60

1-2-61

1-2-62

1-2-63

1-2-64

1-2-65

1-2-66

1-2-67

1-2-68

1-2-69

1-2-70

1-2-71

1-2-72

1-2-73

1-2-74

1-2-75

1-2-76

1-2-77

1-2-78

1-2-79

1-2-80

1-3-1 

1-3-2 

1-3-3 

1-3-4 

1-3-5 

1-3-6 

1-3-7 

1-3-8 

1-3-9 

1-3-10

1-3-11

1-3-12

1-3-13

1-3-14

1-3-15

1-3-16

1-3-17

1-3-18

1-3-19

1-3-20

1-4-1 

1-4-2 

1-4-3 

1-4-4 

1-4-5 

1-4-6 

1-4-7 

1-4-8 

1-4-9 

1-4-10

1-4-11

1-4-12

1-4-13

1-4-14

1-4-15

1-4-16

1-4-17

1-4-18

1-4-19

1-4-20

1-5-1 

1-5-2 

1-5-3 

1-5-4 

1-5-5 

1-5-6 

1-5-7 

1-5-8 

1-5-9 

1-5-10

1-5-11

1-5-12

1-5-13

1-5-14

1-5-15

1-5-16

1-5-17

1-5-18

1-5-19

1-5-20

2. Examples of Composition

The invention will be described in greater detail by way of Examples.The Examples include a typical example, and therefore the invention isnot limited by the Examples. For example, in addition to compositions inUse Examples, the invention includes a mixture of a composition in UseExample 1 and a composition in Use Example 2. The invention alsoincludes a mixture prepared by mixing at least two of the compositionsin the Use Examples. Compounds in the Use Examples were representedusing symbols according to definitions in Table 4 described below. InTable 4, the configuration of 1,4-cyclohexylene is trans. Aparenthesized number next to a symbolized compound in the Use Examplesrepresents a chemical formula to which the compound belongs. A symbol(-) means a liquid crystal compound different from compounds (1) to(15). A proportion (percentage) of the liquid crystal compound isexpressed in terms of weight percent (% by weight) based on the weightof the liquid crystal composition containing no additives. Values of thephysical properties of the composition are summarized in a last part.The physical properties were measured according to the methods describedabove, and measured values are directly described (withoutextrapolation).

TABLE 4 Method for description of compounds using symbols R—(A₁)—Z₁— . .. —Z_(n)—(A_(n))—R′ 1) Left-terminal group R— Symbol C_(n)H_(2n+1)— n-C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn— CH₂═CH— V—C_(n)H_(2n + 1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn—C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn— CF₂═CH— VFF— CF₂═CH—C_(n)H_(2n)—VFFn— 2) Right-terminal group —R′ Symbol —C_(n)H_(2n+1) -n—OC_(n)H_(2n+1) —On —COOCH₃ —EMe —CH═CH₂ —V —CH═CH—C_(n)H_(2n+1) —Vn—C_(n)H_(2n)—CH═CH₂ —nV —C_(m)H_(2m)—CH═CH —C_(n)H_(2n+1) —mVn —CH═CF₂—VFF —F —F —Cl —CL —OCF₃ —OCF3 —OCF₂H —OCF2H —CF₃ —CF3 —OCH═CH—CF₃—OVCF3 —C≡N —C 3) Bonding group —Z_(n)— Symbol —C_(n)H_(2n)— n —COO— E—CH═CH— V —CH₂O-A50s 1O —OCH₂— O1 —CF₂O— X —C≡C— T 4) Ring structure—A_(n)— Symbol

H

B

B(F)

B(2F)

B(F, F)

B(2F, 5F)

B(2F, 3F)

Py

G

ch

Dh

dh

Cro(7F, 8F)

BF(1F, 2F, 8F, 9F)

BF(1F, 2F, 8F) 5) Examples of description Example 1.5-H1OBF(1F,2F,8F,9F)-3

Example 2. 5-H1OBF(1F,2F,8F)-3

Use Example 1

5-H1OBF(1F,2F,8F,9F)-3 (1-2-43) 5% 3-HB-O2  (2-5) 15% 2-BTB-1  (2-10) 3%3-HHB-1  (3-1) 8% 3-HHB-O1  (3-1) 5% 3-HHB-3  (3-1) 13% 3-HHB-F (13-1)4% 2-HHB(F)-F (13-2) 6% 3-HHB(F)-F (13-2) 8% 5-HHB(F)-F (13-2) 6%3-HHB(F,F)-F (13-3) 4% 3-HHEB-F (13-10) 4% 5-HHEB-F (13-10) 5% 2-HB-C(15-1) 5% 3-HB-C (15-1) 9% NI = 103.0° C.; η = 23.5 mPa · s; Δn = 0.104;Δε = 3.7.

Use Example 2

5O-BF(1F,2F,8F,9F)-3 (1-1-7) 3% 3-HH-4  (2-1) 10% 3-HB-O2  (2-5) 10%3-HB-CL (12-2) 10% 3-HHB(F,F)-F (13-3) 5% 3-HBB(F,F)-F (13-24) 25%5-HBB(F,F)-F (13-24) 23% 5-HBB(F)B-2  (4-5) 7% 5-HBB(F)B-3  (4-5) 7% NI= 77.3° C.; η = 23.0 mPa · s; Δn = 0.123; Δε = 4.8.

Use Example 3

5-Dh1OBF(1F,2F,8F,9F)-O2 (1-2-50) 4% 3-HB-O2  (2-5) 8% 7-HB(F,F)-F(12-4) 4% 2-HHB(F)-F (13-2) 8% 3-HHB(F)-F (13-2) 8% 5-HHB(F)-F (13-2) 8%2-HBB-F (13-22) 5% 3-HBB-F (13-22) 5% 5-HBB-F (13-22) 3% 2-HBB(F)-F(13-23) 6% 3-HBB(F)-F (13-23) 8% 5-HBB(F)-F (13-23) 15% 3-HBB(F,F)-F(13-24) 8% 5-HBB(F,F)-F (13-24) 10%

Use Example 4

5-BBF(1F,2F,8F,9F)-O2 (1-2-22) 6% 3-HH-4  (2-1) 10% 3-HH-5  (2-1) 4%1O1-HBBH-5  (4-1) 4% 5-HB-CL (12-2) 13% 3-HHB-F (13-1) 4% 3-HHB-CL(13-1) 4% 4-HHB-CL (13-1) 4% 3-HHB(F)-F (13-2) 8% 4-HHB(F)-F (13-2) 8%5-HHB(F)-F (13-2) 8% 7-HHB(F)-F (13-2) 6% 5-HBB(F)-F (13-23) 4%3-HHBB(F,F)-F (14-6) 3% 4-HHBB(F,F)-F (14-6) 3% 5-HHBB(F,F)-F (14-6) 4%3-HH2BB(F,F)-F (14-15) 4% 4-HH2BB(F,F)-F (14-15) 3%

Use Example 5

5-HBF(1F,2F,8F,9F)-O2 (1-2-5) 3% 1O1-HBBH-4  (4-1) 4% 1O1-HBBH-5  (4-1)3% 3-HHB(F,F)-F (13-3) 9% 3-H2HB(F,F)-F (13-15) 8% 4-H2HB(F,F)-F (13-15)10% 5-H2HB(F,F)-F (13-15) 8% 3-HBB(F,F)-F (13-24) 17% 5-HBB(F,F)-F(13-24) 19% 3-H2BB(F,F)-F (13-27) 11% 5-HHBB(F,F)-F (14-6) 3%3-HH2BB(F,F)-F (14-15) 3% 5-HHEBB-F (14-17) 2%

Use Example 6

5O-BF(1F,2F,8F,9F)-O2 (1-1-2) 5% 5-HBBH-3  (4-1) 3% 3-HB(F)BH-3  (4-2)3% 5-HB-F (12-2) 12% 6-HB-F (12-2) 9% 7-HB-F (12-2) 7% 2-HHB-OCF3 (13-1)5% 3-HHB-OCF3 (13-1) 5% 4-HHB-OCF3 (13-1) 7% 5-HHB-OCF3 (13-1) 4%3-HHB(F,F)-OCF2H (13-3) 5% 3-HHB(F,F)-OCF3 (13-3) 6% 3-HH2B-OCF3 (13-4)3% 5-HH2B-OCF3 (13-4) 4% 3-HH2B(F)-F (13-5) 3% 3-HBB(F)-F (13-23) 12%5-HBB(F)-F (13-23) 7%

Use Example 7

V-H1OBF(1F,2F,8F,9F)-3 (1-2-46) 3% 3-HH-4  (2-1) 8% 3-HB-O2  (2-5) 4%3-HHB-1  (3-1) 3% 5-HB-CL (12-2) 10% 3-HHB(F,F)-F (13-3) 8%3-HHEB(F,F)-F (13-12) 8% 4-HHEB(F,F)-F (13-12) 5% 5-HHEB(F,F)-F (13-12)5% 3-HBB(F,F)-F (13-24) 15% 5-HBB(F,F)-F (13-24) 13% 2-HBEB(F,F)-F(13-39) 4% 3-HBEB(F,F)-F (13-39) 4% 5-HBEB(F,F)-F (13-39) 4%3-HHBB(F,F)-F (14-6) 6%

Use Example 8

5-H1OBF(1F,2F,8F)-3 (1-2-45) 5% 3-HB-CL (12-2) 5% 5-HB-CL (12-2) 4%3-HHB-OCF3 (13-1) 5% V-HHB(F)-F (13-2) 5% 3-HHB(F)-F (13-2) 3%5-HHB(F)-F (13-2) 4% 3-H2HB-OCF3 (13-13) 3% 5-H2HB(F,F)-F (13-15) 5%5-H4HB-OCF3 (13-19) 15% 3-H4HB(F,F)-CF3 (13-21) 8% 5-H4HB(F,F)-CF3(13-21) 10% 5-H4HB(F,F)-F (13-21) 7% 2-H2BB(F)-F (13-26) 5% 3-H2BB(F)-F(13-26) 8% 3-HBEB(F,F)-F (13-39) 8%

Use Example 9

5-H1OBF(1F,2F,8F,9F)-3 (1-2-43) 4% 3-HH-4  (2-1) 5% 3-HH-5  (2-1) 10%3-HB-O2  (2-5) 13% 3-HHB-1  (3-1) 8% 3-HHB-O1  (3-1) 8% 5-HB-CL (12-2)15% 7-HB(F,F)-F (12-4) 5% 2-HHB(F)-F (13-2) 7% 3-HHB(F)-F (13-2) 4%5-HHB(F)-F (13-2) 5% 3-HHB(F,F)-F (13-3) 6% 3-H2HB(F,F)-F (13-15) 5%4-H2HB(F,F)-F (13-15) 5% NI = 73.4° C.; η = 18.6 mPa · s; Δn = 0.077; Δε= 2.2.

Use Example 10

5O-BF(1F,2F,8F,9F)-3 (1-1-7) 3% 3-HH-4  (2-1) 9% 3-HH-5  (2-1) 9%3-HB-O2  (2-5) 13% 5-HB-CL (12-2) 4% 7-HB(F)-F (12-3) 5% 2-HHB(F,F)-F(13-3) 4% 3-HHB(F,F)-F (13-3) 4% 3-HHEB-F (13-10) 9% 5-HHEB-F (13-10) 8%3-HHEB(F,F)-F (13-12) 8% 4-HHEB(F,F)-F (13-12) 6% 3-GHB(F,F)-F (13-109)5% 4-GHB(F,F)-F (13-109) 6% 5-GHB(F,F)-F (13-109) 7% NI = 70.4° C.; η =21.4 mPa · s; Δn = 0.071; Δε = 5.5.

Use Example 11

5-Dh1OBF(1F,2F,8F,9F)-O2 (1-2-50) 6% 3-HH-4 (2-1) 5% 3-HH-V (2-1) 5%3-HB-O1 (2-5) 12% 3-HB-O2 (2-5) 3% 3-HHB-1 (3-1) 5% 3-HB(2F,3F)-O2 (5-1)10% 5-HB(2F,3F)-O2 (5-1) 10% 2-HHB(2F,3F)-1 (6-1) 8% 3-HHB(2F,3F)-1(6-1) 12% 3-HHB(2F,3F)-O2 (6-1) 11% 5-HHB(2F,3F)-O2 (6-1) 13%

Use Example 12

5-BBF(1F,2F,8F,9F)-O2 (1-2-22) 5% 2-HH-5 (2-1) 3% 3-HH-4 (2-1) 10%3-HH-5 (2-1) 5% 3-HH-V (2-1) 10% 3-HB-O2 (2-5) 8% 3-HHB-1 (3-1) 3%3-HHB-3 (3-1) 4% 3-HHB-O1 (3-1) 3% 3-H2B(2F,3F)-O2 (5-4) 10%5-H2B(2F,3F)-O2 (5-4) 10% 2-HBB(2F,3F)-O2 (6-7) 4% 3-HBB(2F,3F)-O2 (6-7)9% 5-HBB(2F,3F)-O2 (6-7) 9% 3-HHB(2F,3CL)-O2 (6-12) 4% 3-HBB(2F,3CL)-O2(6-13) 3%

Use Example 13

5-HBF(1F,2F,8F,9F)-O2 (1-2-5) 3% 5O-BF(1F,2F,8F,9F)-O2 (1-1-2) 4% 2-HH-3(2-1) 15% 2-HH-5 (2-1) 3% 3-HH-4 (2-1) 10% 3-HB-O2 (2-5) 3% 1-BB-3 (2-8)9% 3-HHB-1 (3-1) 4% 3-HHB-O1 (3-1) 3% 5-B(F)BB-2 (3-8) 2% 3-BB(2F,3F)-O2(5-3) 7% 5-BB(2F,3F)-O2 (5-3) 4% 2-HH1OB(2F,3F)-O2 (6-5) 15%3-HH1OB(2F,3F)-O2 (6-5) 18%

Use Example 14

V-H1OBF(1F,2F,8F,9F)-3 (1-2-46) 4% 2-HH-3 (2-1) 12% 7-HB-1 (2-5) 11%5-HB-O2 (2-5) 11% 5-HBB(F)B-2 (4-5) 7% 5-HBB(F) B-3 (4-5) 7%3-HB(2F,3F)-O2 (5-1) 15% 5-HB(2F,3F)-O2 (5-1) 16% 5-HBB(2F,3F)-O2 (6-7)6% 3-HHB(2F,3CL)-O2 (6-12) 3% 4-HHB(2F,3CL)-O2 (6-12) 3%5-HHB(2F,3CL)-O2 (6-12) 2% 3-HH1OCro(7F,8F)-5 (9-6) 3%

Use Example 15

5-H1OBF(1F,2F,8F)-3 (1-2-45) 3% 3-HH-V (2-1) 30% 1-BB-3 (2-8) 8% 3-HHB-1(3-1) 8% 5-B(F)BB-2 (3-8) 7% 3-BB(2F,3F)-O2 (5-3) 12% 2-HH1OB(2F,3F)-O2(6-5) 18% 3-HH1OB(2F,3F)-O2 (6-5) 14%

Use Example 16

5-H1OBF(1F,2F,8F,9F)-3 (1-2-43) 5% 5O-BF(1F,2F,8F,9F)-3 (1-1-7) 5%2-HH-3 (2-1) 5% 3-HH-V (2-1) 5% 3-HH-V1 (2-1) 8% 1V2-HH-1 (2-1) 8%1V2-HH-3 (2-1) 7% 3-HHB-1 (3-1) 3% 3-HHB-3 (3-1) 2% 3-BB(2F,3F)-O2 (5-3)8% 5-BB(2F,3F)-O2 (5-3) 4% 3-H1OB(2F,3F)-O2 (5-5) 7% 3-HDhB(2F,3F)-O2(6-3) 5% 2-HH1OB(2F,3F)-O2 (6-5) 6% 3-HH1OB(2F,3F)-O2 (6-5) 14%2-BB(2F,3F)B-3 (7-1) 8% NI = 74.0° C.; η = 25.6 mPa · s.; Δn = 0.107; Δε= −4.4.

Use Example 17

5-Dh1OBF(1F,2F,8F,9F)-O2 (1-2-50) 4% 5-HH-VFF (2-1) 25% 2-BTB-1  (2-10)12% 3-HHB-1 (3-1) 6% VFF-HHB-1 (3-1) 6% VFF2-HHB-1 (3-1) 8% 3-H2BTB-2 (3-17) 5% 3-H2BTB-3  (3-17) 5% 3-H2BTB-4  (3-17) 5% 3-HB-C (15-1)  18%1V2-BEB(F,F)-C (15-15) 6%

Use Example 18

5-BBF(1F,2F,8F,9F)-O2 (1-2-22) 6% 3-HH-V  (2-1) 36% 3-HH-V1  (2-1) 8%3-HHB-1  (3-1) 5% V-HHB-1  (3-1) 4% V2-BB(F)B-1  (3-6) 5% 3-HHEH-5 (3-13) 5% 1V2-BB-F (12-1) 3% 3-BB(F,F)XB(F,F)-F (13-97) 8%3-HHBB(F,F)-F (14-6) 3% 5-HB(F)B(F,F)XB(F,F)-F (14-41) 4%3-BB(F)B(F,F)XB(F,F)-F (14-47) 3% 4-BB(F)B(F,F)XB(F,F)-F (14-47) 5%5-BB(F)B(F,F)XB(F,F)-F (14-47) 5%

Use Example 1

5-HBF(1F,2F,8F,9F)-O2 (1-2-5) 3% 3-HH-V  (2-1) 42% 3-HH-V1  (2-1) 7%3-HHB-1  (3-1) 4% V-HHB-1  (3-1) 5% V2-BB(F)B-1  (3-6) 5% 3-HHEH-5 (3-13) 3% 1V2-BB-F (12-1) 3% 3-BB(F,F)XB(F,F)-F (13-97) 4%3-GB(F,F)XB(F,F)-F (13-113) 4% 3-HHBB(F,F)-F (14-6) 3%3-BB(F)B(F,F)XB(F,F)-F (14-47) 5% 4-BB(F)B(F,F)XB(F,F)-F (14-47) 5%5-BB(F)B(F,F)XB(F,F)-F (14-47) 3% 3-GB(F)B(F,F)XB(F,F)-F (14-57) 4%

Use Example 20

5O-BF(1F,2F,8F,9F)-O2 (1-1-2) 4% 3-HH-4 (2-1) 6% 3-HH-VFF (2-1) 5%3-HB-O1 (2-5) 15% 1-BB-5 (2-8) 5% 3-HHB-1 (3-1) 6% V-HB(2F,3F)-O2 (5-1)5% 5-HB(2F,3F)-O2 (5-1) 12% 2-HHB(2F,3F)-1 (6-1) 10% 3-HHB(2F,3F)-1(6-1) 10% 3-HHB(2F,3F)-O2 (6-1) 11% 5-HHB(2F,3F)-O2 (6-1) 11%

Use Example 21

V-H1OBF(1F,2F,8F,9F)-3 (1-2-46) 3% 5-H1OBF(1F,2F,8F)-3 (1-2-45) 3%2-HH-3 (2-1) 10% 2-HH-5 (2-1) 6% 7-HB-1 (2-5) 5% 5-HB-O2 (2-5) 7% 1-BB-3(2-8) 5% 5-HBB(F)B-2 (4-5) 10% 5-HBB(F)B-3 (4-5) 8% 3-HB(2F,3F)-O2 (5-1)13% 5-HB(2F,3F)-O2 (5-1) 10% 2-H1OB(2F,3F)-O2 (5-5) 3% 3-H1OB(2F,3F)-O2(5-5) 3% V-HHB(2F,3F)-O2 (6-1) 3% V2-HHB(2F,3F)-O2 (6-1) 3%5-HHB(2F,3CL)-O2 (6-12) 2% 3-HH1OCro(7F,8F)-5 (9-6) 6%

Use Example 22

5-H1OBF(1F,2F,8F,9F)-3 (1-2-43) 3% 2-HH-5 (2-1) 3% 3-HH-4 (2-1) 12%3-HH-5 (2-1) 5% 3-HB-O2 (2-5) 13% 3-HHB-1 (3-1) 4% 3-HHB-3 (3-1) 3%3-HHB-O1 (3-1) 3% 3-DhB(2F,3F)-O2 (5-2) 3% 2-BB(2F,3F)-O2 (5-3) 8%5-H2B(2F,3F)-O2 (5-4) 12% 3-HH2B(2F,3F)-O2 (6-4) 4% V-HBB(2F,3F)-O2(6-7) 4% 3-HBB(2F,3F)-O2 (6-7) 9% 5-HBB(2F,3F)-O2 (6-7) 9%3-HHB(2F,3CL)-O2 (6-12) 5% NI = 81.9° C.; η = 25.2 mPa · s; Δn = 0.106;Δε = −4.4.

Use Example 23

5O-BF(1F,2F,8F,9F)-3 (1-1-7) 6% 2-HH-3 (2-1) 6% 3-HH-V1 (2-1) 8%1V2-HH-1 (2-1) 8% 1V2-HH-3 (2-1) 7% V-HHB-1 (3-1) 3% V2-HHB-1 (3-1) 3%3-HHB-1 (3-1) 3% 3-HHB-3 (3-1) 2% V2-BB(2F,3F)-O2 (5-3) 4%5-BB(2F,3F)-O2 (5-3) 4% 3-H1OB(2F,3F)-O2 (5-5) 5% 3-HDhB(2F,3F)-O2 (6-3)7% 3-HH1OB(2F,3F)-O2 (6-5) 19% 3-dhBB(2F,3F)-O2 (6-9) 3%3-HchB(2F,3F)-O2 (6-18) 3% 2-BB(2F,3F)B-3 (7-1) 9% NI = 89.3° C.; η =24.1 mPa · s; Δn = 0.112; Δε = −4.1.

Use Example 24

5-Dh1OBF(1F,2F,8F,9F)-O2 (1-2-50) 3% 2-HH-3 (2-1) 14% 3-HH-4 (2-1) 10%3-HB-O2 (2-5) 3% 1-BB-3 (2-8) 10% 3-HHB-1 (3-1) 5% 3-HHB-O1 (3-1) 4%V-HBB-2 (3-4) 5% 5-B(F)BB-2 (3-8) 2% 3-BB(2F,3F)-O2 (5-3) 9%5-BB(2F,3F)-O2 (5-3) 5% 2-HH1OB(2F,3F)-O2 (6-5) 10% 3-HH1OB(2F,3F)-O2(6-5) 20%

Use Example 25

5-BBF(1F,2F,8F,9F)-O2 (1-2-22) 3% 3-HH-V  (2-1) 35% 3-HH-V1  (2-1) 6%3-HHB-1  (3-1) 5% V-HHB-1  (3-1) 4% V2-BB(F)B-1  (3-6) 3% 3-HHEH-5 (3-13) 4% 1V2-BB-F (12-1) 3% 3-BB(F,F)XB(F,F)-F (13-97) 4%3-GB(F,F)XB(F,F)-F (13-113) 3% 3-HHBB(F,F)-F (14-6) 3%3-BB(F)B(F,F)XB(F,F)-F (14-47) 3% 4-BB(F)B(F,F)XB(F,F)-F (14-47) 4%5-BB(F)B(F,F)XB(F,F)-F (14-47) 3% 3-GB(F)B(F,F)XB(F,F)-F (14-57) 3%4-GB(F)B(F,F)XB(F,F)-F (14-57) 4% 5-GB(F)B(F,F)XB(F,F)-F (14-57) 5%3-GB(F)B(F,F)XB(F,F)-F (14-57) 5%

Use Example 26

5-HBF(1F,2F,8F,9F)-O2 (1-2-5) 4% 3-HH-V  (2-1) 38% 3-HH-V1  (2-1) 5%3-HHB-1  (3-1) 3% V-HHB-1  (3-1) 4% V2-BB(F)B-1  (3-6) 4% 3-HHEH-5 (3-13) 4% 1V2-BB-F (12-1) 5% 3-BB(F,F)XB(F,F)-F (13-97) 9%3-HHBB(F,F)-F (14-6) 3% 5-HB(F)B(F,F)XB(F,F)-F (14-41) 3%3-BB(F)B(F,F)XB(F,F)-F (14-47) 3% 4-BB(F)B(F,F)XB(F,F)-F (14-47) 5%5-BB(F)B(F,F)XB(F,F)-F (14-47) 3% 2-dhBB(F,F)XB(F,F)-F (14-50) 3%3-dhBB(F,F)XB(F,F)-F (14-50) 4%

Use Example 27

5O-BF(1F,2F,8F,9F)-O2 (1-1-2) 5% 3-HH-V  (2-1) 34% 3-HH-V1  (2-1) 5%3-HHB-1  (3-1) 4% V-HHB-1  (3-1) 5% V2-BB(F)B-1  (3-6) 4% 3-HHEH-5 (3-13) 3% 1V2-BB-F (12-1) 3% 3-BB(F,F)XB(F,F)-F (13-97) 5%3-GB(F,F)XB(F,F)-F (13-113) 3% 3-HHBB(F,F)-F (14-6) 3%3-BB(F)B(F,F)XB(F,F)-F (14-47) 3% 4-BB(F)B(F,F)XB(F,F)-F (14-47) 6%5-BB(F)B(F,F)XB(F,F)-F (14-47) 3% 3-GB(F)B(F,F)XB(F,F)-F (14-57) 4%3-GBB(F,F)XB(F,F)-F (14-58) 3% 4-GBB(F,F)XB(F,F)-F (14-58) 3%5-GBB(F,F)XB(F,F)-F (14-58) 4%

Use Example 28

5-B(F)BF(1F,2F,8F,9F)-O2 (1-2-29) 4% 3-HH-V  (2-1) 31% 3-HH-V1  (2-1) 5%3-HHB-1  (3-1) 4% V-HHB-1  (3-1) 5% 3-HBB-2  (3-4) 5% V2-BB(F)B-1  (3-6)5% 3-HHEH-3  (3-13) 3% 3-HHEH-5  (3-13) 3% 1V2-BB-F (12-1) 3%3-GB(F)B(F)-F (13) 3% 3-BB(F)B(F,F)-CF3 (13-69) 3% 3-BB(F)B(F,F)-F(13-69) 3% 3-GB(F,F)XB(F,F)-F (13-113) 3% 3-HBB(F,F)XB(F,F)-F (14-38) 3%3-BB(F)B(F,F)XB(F)-F (14-46) 3% 3-BB(F,F)XB(F)B(F,F)-F (14-56) 4%3-GB(F)B(F,F)XB(F,F)-F (14-57) 5% 4-GB(F)B(F,F)XB(F,F)-F (14-57) 3%5-GB(F)B(F,F)XB(F,F)-F (14-57) 2% NI = 76.3° C.; Δn = 0.100; Δε = 5.8.

Use Example 29

5-Dh1OBF(1F,2F,8F,9F)-3 (1-2-49) 3% 3-HH-V  (2-1) 32% 3-HH-V1  (2-1) 5%5-HH-V  (2-1) 5% 3-HHB-1  (3-1) 4% V-HHB-1  (3-1) 5% 2-BB(F)B-3  (3-6)5% 3-HHEH-5  (3-13) 3% 1V2-BB-F (12-1) 3% 3-BB(F,F)XB(F,F)-F (13-97) 10%3-GB(F)B(F)B(F)-F (14) 3% 3-HHBB(F,F)-F (14-6) 3% 3-HBBXB(F,F)-F (14-32)3% 5-HB(F)B(F,F)XB(F,F)-F (14-41) 5% 3-GBB(F)B(F,F)-F (14-55) 3%4-GBB(F)B(F,F)-F (14-55) 5% 3-BB(2F,3F)XB(F,F)-F (—) 3% NI = 87.0° C.; η= 21.0 mPa · s; Δn = 0.102; Δε = 4.1.

Use Example 30

5-B(F)BF(1F,2F,8F,9F)-O2 (1-2-29) 3% 3-HH-V  (2-1) 31% 3-HH-V1  (2-1) 7%V-HH-V1  (2-1) 6% 3-HHB-1  (3-1) 4% V-HHB-1  (3-1) 5% 1-BB(F)B-2V  (3-6)4% 3-HHEBH-3  (4-6) 3% 1V2-BB-F (12-1) 3% 3-HHXB(F,F)-F (13-100) 5%3-HHXB(F,F)-CF3 (13-100) 3% 3-GB(F,F)XB(F,F)-F (13-113) 4%3-GB(F)B(F,F)-F (13-116) 4% 3-HHBB(F,F)-F (14-6) 3%3-BB(F)B(F,F)XB(F,F)-F (14-47) 3% 4-BB(F)B(F,F)XB(F,F)-F (14-47) 5%5-BB(F)B(F,F)XB(F,F)-F (14-47) 3% 3-GB(F)B(F,F)XB(F,F)-F (14-57) 4% NI =89.1° C.; Δn = 0.105; Δε = 5.1.

Use Example 31

5-Dh1OBF(1F,2F,8F,9F)-3 (1-2-49) 3% 2-HH-3 (2-1) 21% 4-HH-V (2-1) 9%3-HB-O2 (2-5) 2% 1-BB-3 (2-8) 5% 3-HHB-1 (3-1) 3% 3-HHB-O1 (3-1) 3%V-HBB-2 (3-4) 3% 5-B(F)BB-2 (3-8) 3% 2O-B(2F,3F)B(F)-O2 (5) 9%4O-B(2F,3F)B(F)-O2 (5) 6% 2-HH1OB(2F,3F)-O2 (6-5) 12% 3-HH1OB(2F,3F)-O2(6-5) 13% 3-HB(2F,3F)B-2 (7) 4% V-HH2BB(2F,3F)-O2 (—) 4% NI = 77.6° C.;η = 22.9 mPa · s; Δn = 0.102; Δε = −3.3.

Use Example 32

5-B(F)BF(1F,2F,8F,9F)-O2 (1-2-29) 4% 3-HH-V (2-1) 25% 1-BB-3 (2-8) 7%3-HHB-1 (3-1) 8% 5-B(F)BB-2 (3-8) 5% 3-BB(2F,3F)-O2 (5-3) 12%2O-B(2F,3F)B(F)H-3 (6) 6% 2-HH1OB(2F,3F)-O2 (6-5) 15% 3-HH1OB(2F,3F)-O2(6-5) 12% 5-HFLF4-3 (—) 3% 3-H2BBB(2F,3F)-O2 (—) 3% NI = 84.6° C.; Δn =0.121; Δε = −3.6.

INDUSTRIAL APPLICABILITY

A liquid crystal compound of the invention has good physical properties.A liquid crystal composition containing the compound can be widelyapplied to a liquid crystal display device used in a personal computer,a television and so forth.

What is claimed is:
 1. A compound, represented by formula (1):

wherein, in formula (1), R¹ and R² are independently hydrogen or alkylhaving 1 to 15 carbons, and in the alkyl, at least one piece of —CH₂—may be replaced by —O—, —S—, —CO— or —SiH₂, and at least one piece of—CH₂CH₂— may be replaced by —CH═CH— or —C≡C—, and in the groups, atleast one hydrogen may be replaced by fluorine or chlorine; A¹, A² andA³ are independently 1,2-cyclopropylene, 1,3-cyclobutylene,1,3-cyclopentylene, 1,4-cyclohexylene, 1,4-cycloheptylene,1,4-phenylene, decahydronaphthalene-2,6-diyl,1,2,3,4-tetrahydronaphthalene-2,6-diyl, naphthalene-2,6-diyl,9,10-dihydrophenanthrene-2,7-diyl, 9H-xanthene-2,6-diyl or9H-fluorene-2,7-diyl, and in the groups, at least one piece of —CH₂— maybe replaced by —O—, —S—, —CO— or —SiH₂—, and at least one piece of—CH₂CH₂— may be replaced by —CH═CH— or —CH═N—, and in the divalentgroups, at least one hydrogen may be replaced by fluorine, chlorine,—C≡N, —CF₃, —CHF₂, —CH₂F, —OCF₃, —OCHF₂ or —OCH₂F; Z¹, Z² and Z³ areindependently a single bond or alkylene having 1 to 6 carbons, and inthe alkylene, at least one piece of —CH₂— may be replaced by —O—, —S—,—CO— or —SiH₂—, and one or two pieces of —CH₂CH₂— may be replaced by—CH═CH— or —C≡C—, and in the divalent groups, at least one hydrogen maybe replaced by fluorine or chlorine; Y¹, Y², Y³ and Y⁴ are independentlyhydrogen, fluorine, chlorine, —CF₃ or —CHF₂, and at least two of Y¹, Y²,Y³ and Y⁴ is fluorine, chlorine, —CF₃ or —CHF₂; and a, b and c areindependently 0 or 1, and a sum of a, b and c is 0 to
 3. 2. The compoundaccording to claim 1, wherein, in formula (1), A¹, A² and A³ areindependently 1,4-cyclohexylene, 1,4-cycloheptylene,1,4-cyclohexenylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene, tetrahydropyran-2,5-diyl,1,3-dioxane-2,5-diyl, pyridine-2,5-diyl, pyrimidine-2,5-diyl,decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl ornaphthalene-2,6-diyl.
 3. The compound according to claim 1, wherein, informula (1), Z¹, Z² and Z³ are independently a single bond, —(CH₂)₂—,—CH═CH—, —C≡C—, —COO—, —OCO—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂— or —CF═CF—.4. The compound according to claim 1, represented by any one of formulas(1-1) to (1-5):

wherein, in formulas (1-1) to (1-5), R¹ and R² are independentlyhydrogen, alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons,alkoxy having 1 to 10 carbons or alkenyloxy having 2 to 10 carbons, andin the groups, at least one hydrogen may be replaced by fluorine; ringA¹, ring A² and ring A³ are independently 1,4-cyclohexylene,1,4-cyclohexenylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene or tetrahydropyran-2,5-diyl; Z¹, Z² and Z³are independently a single bond, —(CH₂)₂—, —C≡C—, —CF₂O—, —OCF₂—, —CH₂O—or —OCH₂—; and Y¹, Y², Y³ and Y⁴ are independently hydrogen, fluorine,chlorine, —CF₃ or —CHF₂, and at least two of Y¹, Y², Y³ and Y⁴ isfluorine, chlorine, —CF₃ or —CHF₂.
 5. The compound according to claim 1,represented by any one of formulas (1-6) to (1-11):

wherein, in formulas (1-6) to (1-11), R¹ and R² are independently alkylhaving 1 to 10 carbons, alkenyl having 2 to 10 carbons, alkoxy having 1to 10 carbons or alkenyloxy having 2 to 10 carbons, and in the groups,at least one hydrogen may be replaced by fluorine; Z¹ is a single bond,—(CH₂)₂—, —CH₂O— or —OCH₂—; Y¹, Y², Y³ and Y⁴ are independently hydrogenor fluorine, and at least two of Y¹, Y², Y³ and Y⁴ is fluorine; and L¹and L² are independently hydrogen or fluorine.
 6. The compound accordingto claim 1, represented by any one of formulas (1-12) to (1-14):

wherein, in formulas (1-12) to (1-14), R¹ and R² are independently alkylhaving 1 to 10 carbons, alkenyl having 2 to 10 carbons or alkoxy having1 to 10 carbons; Z¹ is a single bond, —(CH₂)₂—, —CH₂O— or —OCH₂—; Y¹,Y², Y³ and Y⁴ are independently hydrogen or fluorine, and at least twoof Y¹, Y², Y³ and Y⁴ is fluorine; and L¹ and L² are independentlyhydrogen or fluorine.
 7. The compound according to claim 1, representedby any one of formulas (1-15) to (1-32):

wherein, in formulas (1-15) to formula (1-32), R¹ and R² areindependently alkyl having 1 to 10 carbons, alkenyl having 2 to 10carbons or alkoxy having 1 to 10 carbons; and L¹ and L² areindependently hydrogen or fluorine.
 8. The compound according to claim1, represented by any one of formulas (1-33) to (1-36):

wherein, in formulas (1-33) to (1-36), R¹ and R² are independently alkylhaving 1 to 10 carbons or alkoxy 1 to 10 carbons.
 9. A liquid crystalcomposition, containing at least one compound according to claim
 1. 10.The liquid crystal composition according to claim 9, further containingat least one compound selected from the group of compounds representedby formulas (2) to (4):

wherein, in formulas (2) to (4), R¹¹ and R¹² are independently alkylhaving 1 to 10 carbons or alkenyl having 2 to 10 carbons, and in thealkyl and the alkenyl, at least one piece of —CH₂— may be replaced by—O—, and in the groups, at least one hydrogen may be replaced byfluorine; ring B¹, ring B², ring B³ and ring B⁴ are independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,5-difluoro-1,4-phenylene or pyrimidine-2,5-diyl; and Z¹¹, Z¹² and Z¹³are independently a single bond, —COO—, —CH₂CH₂—, —CH═CH— or —C≡C—. 11.The liquid crystal composition according to claim 9, further containingat least one compound selected from the group of compounds representedby formulas (5) to (11):

wherein, in formulas (5) to (11), R¹³, R¹⁴ and R¹⁵ are independentlyalkyl having 1 to 10 carbons or alkenyl having 2 to 10 carbons, and inthe alkyl and the alkenyl, at least one piece of —CH₂— may be replacedby —O—, and in the groups, at least one hydrogen may be replaced byfluorine, and R¹⁵ may be hydrogen or fluorine; ring C¹, ring C², ring C³and ring C⁴ are independently 1,4-cyclohexylene, 1,4-cyclohexenylene,1,4-phenylene, 1,4-phenylene in which at least one hydrogen may bereplaced by fluorine, tetrahydropyran-2,5-diyl, ordecahydronaphthalene-2,6-diyl; ring C⁵ and ring C⁶ are independently1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene,tetrahydropyran-2,5-diyl or decahydronaphthalene-2,6-diy; Z¹⁴, Z¹⁵, Z¹⁶and Z¹⁷ are independently a single bond, —COO—, —CH₂O—, —OCF₂—, —CH₂CH₂—or —OCF₂CH₂CH₂—; L¹¹ and L¹² are independently fluorine or chlorine; S¹¹is hydrogen or methyl; X is —CHF— or —CF₂—; and j, k, m, n, p, q, r ands are independently 0 or 1, a sum of k, m, n and p is 1 or 2, a sum ofq, r and s is 0, 1, 2 or 3, and t is 1, 2 or
 3. 12. The liquid crystalcomposition according to claim 9, further containing at least onecompound selected from the group of compounds represented by formulas(12) to (14):

wherein, in formulas (12) to (14), R¹⁶ is alkyl having 1 to 10 carbonsor alkenyl having 2 to 10 carbons, and in the alkyl and the alkenyl, atleast one piece of —CH₂— may be replaced by —O—, and in the groups, atleast one hydrogen may be replaced by fluorine; X¹¹ is fluorine,chlorine, —CF₃, —CHF₂, —CH₂F, —OCF₃, —OCHF₂, —OCF₂CHF₂ or —OCF₂CHFCF₃;ring D¹, ring D² and ring D³ are independently 1,4-cyclohexylene,1,4-phenylene, 1,4-phenylene in which at least one hydrogen is replacedby fluorine, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, orpyrimidine-2,5-diyl; Z¹⁸, Z¹⁹ and Z²⁰ are independently a single bond,—COO—, —CH₂O—, —CF₂O—, —OCF₂—, —CH₂CH₂—, —CH═CH—, —C≡C— or —(CH₂)₄—; andL¹³ and L¹⁴ are independently hydrogen or fluorine.
 13. The liquidcrystal composition according to claim 9, further containing at leastone compound selected from the group of compounds represented by formula(15):

wherein, in formula (15), R¹⁷ is alkyl having 1 to 10 carbons or alkenylhaving 2 to 10 carbons, and in the alkyl and the alkenyl, at least onepiece of —CH₂— may be replaced by —O—, and in the groups, at least onehydrogen may be replaced by fluorine; X¹² is —C≡N or —C≡C—C≡N; ring E¹is 1,4-cyclohexylene, 1,4-phenylene, 1,4-phenylene in which at least onehydrogen is replaced by fluorine, tetrahydropyran-2,5-diyl,1,3-dioxane-2,5-diyl, or pyrimidine-2,5-diyl; Z²¹ is a single bond,—COO—, —CH₂O—, —CF₂O—, —OCF₂—, —CH₂CH₂— or —C≡C—; L¹⁵ and L¹⁶ areindependently hydrogen or fluorine; and i is 1, 2, 3 or
 4. 14. A liquidcrystal display device, including the liquid crystal compositionaccording to claim 9.